By  Sir  Oliver  Lodge 

Life  and  Matter 
Continuity 


CONTINUITY 

THE    PRESIDENTIAL  ADDRESS 
TO  THE  BRITISH  ASSOCIA- 
TION FOR  1913 


BY 

SIR  OLIVER  LODGE 

AUTHOR  OF  "LIFE  AND  MATTER,"  ETC. 


SUPPLEMENTED  BY   EXPLANATORY   NOTES 


G.  P.  PUTNAM'S  SONS 

NEW    YORK    AND    LONDON 

IRnfcfeerbocfeer  press 

1914 


COPYRIGHT  1914 

BY 

G.  P  PUTNAM'S  SONS 


"Cbe  fmicfeerbocfcer  ipress,  Hew  Korfe 


SUMMARY  OF  THE  ARGUMENT 

A  marked  feature  of  the  present  scientific 
era  is  the  discovery  of,  and  interest  in,  va- 
rious kinds  of  Atomism;  so  that  Continuity 
seems  in  danger  of  being  lost  sight  of. 

Another  tendency  is  toward  comprehen- 
sive negative  generalisations  from  a  limited 
point  of  view. 

Another  is  to  take  refuge  in  rather  vague 
forms  of  statement,  and  to  shrink  from 
closer  examination  of  the  puzzling  and  the 
obscure. 

Another  is  to  deny  the  existence  of  any- 
thing which  makes  no  appeal  to  organs  of 
sense,  and  no  ready  response  to  laboratory 
experiment. 

Against  these  tendencies  the  author  con- 
tends. He  urges  a  belief  in  ultimate  con- 
tinuity as  essential  to  science;  he  regards 
scientific  concentration  as  an  inadequate 
basis  for  philosophic  generalisation;  he 


iv      Summary  of  the  Argument 

believes  that  obscure  phenomena  may  be 
expressed  simply  if  properly  faced;  and  he 
points  out  that  the  non-appearance  of  any- 
thing perfectly  uniform  and  omnipresent 
is  only  what  should  be  expected,  and  is 
no  argument  against  its  real,  substantial 
existence. 


Natura  non  vincitur  nisi  parendo 


CONTINUITY 

FIRST  let  me  lament  the  catastrophe 
which  has  led  to  my  occupying  the  Chair 
here  in  this  City.  Sir  William  White  was 
a  personal  friend  of  many  here  present, 
and  I  would  that  the  citizens  of  Bir- 
mingham could  have  become  acquainted 
with  his  attractive  personality,  and  heard 
at  first  hand  of  the  strenuous  work  which 
he  accomplished  in  carrying  out  the  be- 
hests of  the  Empire  in  the  construction 
of  its  first  line  of  defence. 

Although  a  British  Association  Address 
is  hardly  an  annual  stocktaking,  it  would 
be  improper  to  begin  this  year  of  Office 
without  referring  to  four  more  of  our 
losses: — One  that  cultured  gentleman, 
amateur  of  science  in  the  best  sense,  who 
was  chosen  to  preside  over  our  Jubilee 
meeting  at  York  thirty-two  years  ago. 
Sir  John  Lubbock,  first  Baron  Avebury, 
cultivated  science  in  a  spirit  of  pure 
enjoyment,  treating  it  almost  as  one  of  the 


2  Presidential  Address 

Arts;  and  he  devoted  social  and  political 
energy  to  the  welfare  of  the  multitude 
of  his  fellows  less  fortunately  situated 
than  himself. 

Through  the  untimely  death  of  Sir 
George  Darwin  the  world  has  lost  a 
mathematical  astronomer  whose  work 
on  the  Tides  and  allied  phenomena  is  a 
monument  of  power  and  achievement. 
So  recently  as  our  visit  to  S.  Africa  he 
occupied  the  Presidential  Chair. 

Within  the  last  month  I  have  heard  of 
the  premature  death  of  John  Milne,  who 
was  apparently  at  the  height  of  his 
energy  and  usefulness.  His  enthusiasm 
and  persevering  work  for  Seismology  has 
resulted  in  an  international  organisation 
centring  round  his  personality.  He  has, 
I  am  told,  left  £1000  to  help  continue 
the  work,  and  it  behoves  us  to  see  that 
no  sinews  of  war  shall  be  lacking  to 
assist  survivors  in  organising  and  con- 
tinuing the  attack  in  this  immensely 
important  field  of  combined  and  co- 
operative research. 


Continuity  3 

By  the  fourth  of  our  major  losses,  I 
mean  the  death  of  the  brilliant  Mathe- 
matician of  a  neighbouring  nation  who 
took  so  comprehensive  and  philosophic  a 
grasp  of  the  intricacies  of  physics,  and 
whose  eloquent  -though  sceptical  exposi- 
tion of  our  laws  and  processes,  and  of  the 
modifications  entailed  in  them  by  recent 
advances,  will  be  sure  to  attract  still 
more  widespread  attention  among  all  to 
whom  the  rather  abstruse  subject-matter 
is  sufficiently  familiar.  I  cannot  say  that 
I  find  myself  in  agreement  with  all  that 
Henri  Poincar6  wrote  or  spoke  in  the 
domain  of  physics,  but  no  physicist  can 
help  being  interested  in  his  mode  of 
presentation;  and  I  may  have  occasion 
to  refer,  in  passing,  to  some  of  the  topics 
with  which  he  dealt. 

And  now,  eliminating  from  our  purview, 
as  is  always  necessary,  a  great  mass  of 
human  activity,  and  limiting  ourselves 
to  a  scrutiny  on  the  side  of  pure  science 
alone,  let  us  ask  what,  in  the  main,  is 
the  characteristic  of  the  promising  though 


4  Presidential  Address 

perturbing  period  in  which  we  live. 
Different  persons  would  give  different 
answers,  but  the  answer  I  venture  to  give 
is — Rapid  progress,  combined  with  Fun- 
damental scepticism. 

Rapid  progress  was  not  characteristic 
of  the  latter  half  of  the  nineteenth 
century, — at  least  not  in  physics.  Fine 
solid  dynamical  foundations  were  laid, 
and  the  edifice  of  knowledge  was  con- 
solidated; but  wholly  fresh  ground  was 
not  being  opened  up,  and  totally  new 
buildings  were  not  expected. 

In  many  cases  the  student  was  led  to  believe 
that  the  main  facts  of  nature  were  all  known, 
that  the  chances  of  any  great  discovery  being 
made  by  experiment  were  vanishingly  small,  and 
that  therefore  the  experimentalist's  work  con- 
sisted in  deciding  between  rival  theories,  or  in 
finding  some  small  residual  effect,  which  might 
add  a  more  or  less  important  detail  to  the 
theory. — Schuster. 

With  the  realisation  of  predicted  ether 
waves  in  1888,  the  discovery  of  X-rays  in 
1895,  spontaneous  radioactivity  in  1896, 


Continuity  5 

and  the  isolation  of  the  electron  in  1898, 
expectation  of  further  achievement  be- 
came vivid;  and  novelties,  experimental, 
theoretical,  and  speculative,  have  been 
showered  upon  us  ever  since  this  century 
began.  That  is  why  I  speak  of  rapid 
progress. 

Of  the  progress  I  shall  say  little, — 
there  must  always  be  some  uncertainty 
as  to  which  particular  achievement  per- 
manently contributes  to  it;  but  I  will 
speak  about  the  fundamental  scepticism. 

Let  me  hasten  to  explain  that  I  do  not 
mean  the  well-worn  and  almost  antique 
theme  of  Theological  scepticism:  that 
controversy  is  practically  in  abeyance 
just  now.  At  any  rate  the  major  con- 
flict is  suspended ;  the  forts  behind  which 
the  enemy  has  retreated  do  not  invite 
attack;  the  territory  now  occupied  by 
him  is  little  more  than  his  legitimate  pro- 
vince. It  is  the  scientific  allies,  now,  who 
are  waging  a  more  or  less  invigorating 
conflict  among  themselves;  with  Phi- 
losophers joining  in.  Meanwhile  the 
ancient  foe  is  biding  his  time  and  hoping 


6  Presidential  Address 

that  from  the  struggle  something  will 
emerge  of  benefit  to  himself.  Some  posi- 
tions, he  feels,  were  too  hastily  abandoned 
and  may  perhaps  be  retrieved;  or,  to 
put  it  without  metaphor,  it  seems  possible 
that  a  few  of  the  things  prematurely 
denied,  because  asserted  on  inconclusive 
evidence,  may,  after  all,  in  some  form  or 
other,  have  really  happened.  Thus  the 
old  theological  bitterness  is  mitigated, 
and  a  temporising  policy  is  either  advo- 
cated or  instinctively  adopted. 

To  illustrate  the  nature  of  the  funda- 
mental scientific  or  philosophic  contro- 
versies to  which,  I  do  refer,  would  require 
almost  as  many  addresses  as  there  are 
Sections  of  the  British  Association;  or 
at  any  rate  as  many  as  there  are  chief 
cities  in  Australia;  and  perhaps  my  suc- 
cessor in  the  Chair  will  continue  the 
theme;  but,  to  exhibit  my  meaning  very 
briefly,  I  may  cite  the  kind  of  dominating 
controversies  now  extant,  employing  as 
far  as  possible  only  a  single  word  in  each 
case  so  as  to  emphasise  the  necessary 
brevity  and  insufficiency  of  the  reference. 


Continuity  7 

In  Physiology  the  conflict  ranges  round  Vital- 
ism. (My  immediate  predecessor  dealt  with 
the  subject  at  Dundee.) 

In  Chemistry  the  debate  concerns  Atomic 
structure.  (My  penultimate  predecessor  is 
well  aware  of  pugnacity  in  that  region.) 

In  Biology  the  dispute  is  on  the  laws  of  In- 
heritance. (My  nominated  successor  is 
likely  to  deal  with  this  subject;  probably 
in  a  way  not  deficient  in  liveliness.) 

And  besides  these  major  controversies,  debate 
is  active  in  other  sections : — 

In  Education,  Curricula  generally  are  being 
overhauled  or  fundamentally  criticised,  and 
revolutionary  ideas  are  promulgated  con- 
cerning the  advantages  of  freedom  for 
infants. 

In  Economic  and  Political  Science,  or  Soci- 
ology, what  is  there  that  is  not  under  dis- 
cussion? Not  property  alone,  nor  land  alone, 
but  everything, — back  to  the  garden  of  Eden 
and  the  inter-relations  of  men  and  women. 

Lastly,  in  the  vast  group  of  Mathematical 
and  Physical  Sciences,  "slurred  over  rather 
than  summed  up  as  Section  A,"  present- 
day  scepticism  concerns  what,  if  I  had  to 
express  it  in  one  word,  I  should  call  Con- 
tinuity. The  full  meaning  of  this  term  will 
hardly  be  intelligible  without  explanation, 
and  I  shall  discuss  it  presently. 


8  Presidential  Address 

Still  more  fundamental  and  deep-rooted 
than  any  of  these  sectional  debates, 
however,  a -critical  examination  of  scien- 
tific foundations  generally  is  going  on; 
and  a  kind  of  philosophic  scepticism  is  in 
the  ascendant,  resulting  in  a  mistrust  of 
purely  intellectual  processes  and  in  a 
recognition  of  the  limited  scope  of  science. 

For  science  is  undoubtedly  an  affair  of 
the  intellect,  it  examines  everything  in  the 
cold  light  of  reason;  and  that  is  its 
strength.  It  is  a  commonplace  to  say  that 
science  must  have  no  likes  or  dislikes, 
must  aim  only  at  truth;  or  as  Bertrand 
Russell  well  puts  it, — 

The  kernel  of  the  scientific  outlook  is  the 
refusal  to  regard  our  own  desires,  tastes,  and 
interests  as  affording  a  key  to  the  understanding 
of  the  world. 

This  exclusive  single-eyed  attitude  of 
science  is  its  strength;  but,  if  pressed 
beyond  the  positive  region  of  usefulness 
into  a  field  of  dogmatic  negation  and 
philosophising,  it  becomes  also  its  weak- 
ness. For  the  nature  of  man  is  a  large 


Continuity  9 

thing,  and  intellect  is  only  a  part  of  it: 
a  recent  part  too,  which  therefore  ne- 
cessarily, though  not  consciously,  suffers 
from  some  of  the  defects  of  newness  and 
crudity,  and  should  refrain  from  imagin- 
ing itself  the  whole — perhaps  it  is  not 
even  the  best  part — of  human  nature. 

The  fact  is  that  some  of  the  best  things 
are,  by  abstraction,  excluded  from  Science, 
though  not  from  Literature  and  Poetry; 
hence  perhaps  an  ancient  mistrust  or 
dislike  of  science,  typified  by  the  Pro- 
methean legend.  Science  is  systematised 
and  metrical  knowledge,  and  in  regions 
where  measurement  cannot  be  applied 
it  has  small  scope;  or,  as  Mr.  Balfour 
said  the  other  day  at  the  opening  of 
a  new  wing  of  the  National  Physical 
Laboratory: 

Science  depends  on  measurement,  and  things 
not  measurable  are  therefore  excluded,  or  tend 
to  be  excluded,  from  its  attention.  But  Life 
and  Beauty  and  Happiness  are  not  measurable. 
[And  then  characteristically  he  adds:]  If  there 
could  be  a  unit  of  happiness,  Politics  might 
begin  to  be  scientific. 


io  .         Presidential  Address 

Emotion  and  Intuition  and  Instinct 
are  immensely  older  than  science,  and  in 
a  comprehensive  survey  of  existence  they 
cannot  be  ignored.  Scientific  men  may 
rightly  neglect  them,  in  order  to  do  their 
proper  work,  but  philosophers  cannot. 

So  Philosophers  have  begun  to  question 
some  of  the  larger  generalisations  of 
science,  and  to  ask  whether  in  the  effort 
to  be  universal  and  comprehensive  we 
have  not  extended  our  laboratory  induc- 
tions too  far.  The  Conservation  of  En- 
ergy, for  instance, — is  it  always  and 
everywhere  valid;  or  may  it  under  some 
conditions  be  disobeyed?  It  would  seem 
as  if  the  second  law  of  Thermodynamics 
must  be  somewhere  disobeyed — at  least 
if  the  age  of  the  Universe  is  both  ways 
infinite, — else  the  final  consummation 
would  have  already  arrived. 

Not  by  Philosophers  only,  but  by  scien- 
tific men  also,  ancient  postulates  are 
being  pulled  up  by  the  roots.  Physicists 
and  Mathematicians  are  beginning  to 
consider  whether  the  long-known  and  well 
established  laws  of  mechanics  hold  true 


Continuity  1 1 

everywhere  and  always,  or  whether  the 
Newtonian  scheme  must  be  replaced  by 
something  more  modern,  something  to 
which  Newton's  laws  of  motion  are  but 
an  approximation. 

Indeed  a  whole  system  of  non-New- 
tonian Mechanics  has  been  devised, 
having  as  its  foundation  the  recently 
discovered  changes  which  must  occur  in 
bodies  moving  at  speeds  nearly  com- 
parable with  that  of  light.  It  turns  out 
in  fact  that  both  Shape  and  Mass  are 
functions  of  Velocity.  As  the  speed 
increases  the  mass  increases  and  the  shape 
is  distorted,  though  under  ordinary  con- 
ditions only  to  an  infinitesimal  extent. 

So  far  I  agree;  I  agree  with  the  state- 
ment of  fact;  but  I  do  not  consider  it  so 
revolutionary  as  to  overturn  Newtonian 
Mechanics.  After  all,  a  variation  of  Mass 
is  familiar  enough,  and  it  would  be  a 
great  mistake  to  say  that  Newton's 
second  law  breaks  down  merely  because 
Mass  is  not  constant.  A  raindrop  is  an 
example  of  variable  mass;  or  the  earth 
may  be,  by  reason  of  meteoric  dust;  or 


12  Presidential  Address 

the  sun,  by  reason  of  radioactivity;  or 
a  locomotive,  by  reason  of  the  emission  of 
steam.  In  fact,  variable  masses  are  the 
commonest,  for  friction  may  abrade  any 
moving  body  to  a  microscopic  extent. 

That  Mass  is  constant  is  only  an  ap- 
proximation. That  Mass  is  equal  to 
ratio  of  Force  and  Acceleration  is  a  de- 
finition, and  can  be  absolutely  accurate. 
It  holds  perfectly  even  for  an  electron 
with  a  speed  near  that  of  light ;  and  it  is 
by  means  of  Newton's  second  law  that 
the  variation  of  Mass  with  Velocity  has 
been  experimentally  observed  and  com- 
pared with  theory. 

I  urge  that  we  remain  with,  or  go  back 
to,  Newton.  I  see  no  reason  against 
retaining  all  Newton's  laws,  discarding 
nothing,  but  supplementing  them  in  the 
light  of  further  knowledge. 

Even  the  laws  of  Geometry  have  been 
overhauled,  and  Euclidean  Geometry  is 
seen  to  be  but  a  special  case  of  more 
fundamental  generalisations.  How  far 
they  apply  to  existing  space,  and  how  far 
Time  is  a  reality  or  an  illusion,  and 


Continuity  13 

whether  it  can  in  any  sense  depend  on  the 
motion  or  the  position  of  an  observer: 
all  these  things  in  some  form  or  other  are 
discussed. 

The  Conservation  of  Matter  also,  that 
mainmast  of  nineteenth  century  chem- 
istry, and  the  existence  of  the  Ether  of 
Space,  that  sheet-anchor  of  nineteenth 
century  physics, — do  they  not  sometimes 
seem  to  be  going  by  the  board? 

Professor  Schuster,  in  his  Indian  lec- 
tures, commented  on  the  modern  receptive 
attitude  as  follows: 

The  state  of  plasticity  and  flux — a  healthy 
state,  in  my  opinion, — in  which  scientific  thought 
of  the  present  day  adapts  itself  to  almost  any 
novelty,  is  illustrated  by  the  complacency  with 
which  the  most  cherished  tenets  of  our  fathers 
are  being  abandoned.  Though  it  was  never  an 
article  of  orthodox  faith  that  chemical  elements 
were  immutable  and  would  not  some  day  be 
resolved  into  simpler  constituents,  yet  the  con- 
servation of  mass  seemed  to  lie  at  the  very 
foundation  of  creation.  But  nowadays  the 
student  finds  little  to  disturb  him,  perhaps  too 
little,  in  the  idea  that  mass  changes  with 
velocity;  and  he  does  not  always  realise  the 


14  Presidential  Address 

full   meaning   of   the  consequences  which   are 
involved. 

This  readiness  to  accept  and  incorpo- 
rate new  facts  into  the  scheme  of  physics 
may  have  led  to  perhaps  an  undue  amount 
of  scientific  scepticism,  in  order  to  right 
the  balance. 

But  a  still  deeper  variety  of  compre- 
hensive scepticism  exists,  and  it  is  argued 
that  all  our  laws  of  nature,  so  laboriously 
ascertained  and  carefully  formulated,  are 
but  conventions  after  all,  not  truths: 
that  we  have  no  faculty  for  ascertaining 
real  truth,  that  our  intelligence  was  not 
evolved  for  any  such  academic  purpose; 
that  all  we  can  do  is  to  express  things  in  a 
form  convenient  for  present  purposes  and 
employ  that  mode  of  expression  as  a 
tentative  and  pragmatically  useful  ex- 
planation. 

Even  explanation,  however,  has  been 
discarded  as  too  ambitious  by  some  men 
of  science,  who  claim  only  the  power  to 
describe.  They  not -only  emphasise  the 
how  rather  than  the  why, — as  is  in  some 
sort  inevitable,  since  explanations  are 


Continuity  15 

never  ultimate — but  are  satisfied  with 
very  abstract  propositions,  and  regard 
mathematical  equations  as  preferable  to, 
because  safer  than,  mechanical  analogies 
or  models. 

To  use  an  acute  and  familiar  expression  of 
Gustav  Kirchhoff,  it  is  the  object  of  science 
to  describe  natural  phenomena,  not  to  explain 
them.  When  we  have  expressed  by  an  equation 
the  correct  relationship  between  different  natural 
phenomena  we  have  gone  as  far  as  we  safely  can, 
and  if  we  go  beyond  we  are  entering  on  purely 
speculative  ground. 

But  the  modes  of  statement  preferred 
by  those  who  distrust  our  power  of  going 
correctly  into  detail  are  far  from  satis- 
factory. Professor  Schuster  describes 
and  comments  on  them  thus: 

Vagueness,  which  used  to  be  recognised  as 
our  great  enemy,  is  now  being  enshrined  as  an 
idol  to  be  worshipped.  We  may  never  know 
what  constitutes  atoms,  or  what  is  the  real 
structure  of  the  ether;  why  trouble,  therefore, 
it  is  said,  to  find  out  more  about  them?  Is  it  not 
safer,  on  the  contrary,  to  confine  ourselves  to  a 
general  talk  on  entropy,  luminiferous  vectors, 


16  Presidential  Address 

and  undefined  symbols  expressing  vaguely  cer- 
tain physical  relationships?  What  really  lies  at 
the  bottom  of  the  great  fascination  which  these 
new  doctrines  exert  on  the  present  generation  is 
sheer  cowardice;  the  fear  of  having  its  errors 
brought  home  to  it .  . 

I  believe  this  doctrine  to  be  fatal  to  a  healthy 
development  of  science.  Granting  the  impos- 
sibility of  penetrating  beyond  the  most  super- 
ficial layers  of  observed  phenomena,  I  would  put 
the  distinction  between  the  two  attitudes  of 
mind  in  this  way:  One  glorifies  our  ignorance, 
while  the  other  accepts  it  as  a  regrettable 
necessity. 

With  this  criticism  I  am  in  accord. 
In  further  illustration  of  the  modern 
sceptical  attitude,  I  quote  from  Poincare : 

Principles  are  conventions  and  definitions  in 
disguise.  They  are,  however,  deduced  from 
experimental  laws,  and  these  laws  have,  so  to 
speak,  been  erected  into  principles  to  which  our 
mind  attributes  an  absolute  value.  .  .  . 

The  fundamental  propositions  of  geometry, 
for  instance  Euclid's  postulate,  are  only  conven- 
tions; and  it  is  quite  as  unreasonable  to  ask  if 
they  are  true  or  false  as  to  ask  if  the  metric 
system  is  true  or  false.  Only,  these  conventions 
are  convenient.  . 


Continuity  17 

Whether  the  ether  exists  or  not  matters  little, 
— let  us  leave  that  to  the  metaphysicians ;  what 
is  essential  for  us  is  that  everything  happens  as 
if  it  existed,  and  that  this  hypothesis  is  found  to 
be  suitable  for  the  explanation  of  phenomena. 
After  all,  have  we  any  other  reason  for  believing 
in  the  existence  of  material  objects?  That,  too, 
is  only  a  convenient  hypothesis. 

A  needed  antidote  against  over-pressing 
these  utterances,  however,  is  provided  by 
Sir  J.  Larmor  in  his  Preface: 

There  has  been  of  late  a  growing  trend  of 
opinion,  prompted  in  part  by  general  philo- 
sophical views,  in  the  direction  that  the  theoreti- 
cal constructions  of  physical  science  are  largely 
factitious,  that  instead  of  presenting  a  valid 
image  of  the  relations  of  things  on  which  further 
progress  can  be  based,  they  are  still  little  better 
than  a  mirage.  .  .  . 

The  best  method  of  abating  this  scepticism 
is  to  become  acquainted  with  the  real  scope  and 
modes  of  application  of  conceptions  which,  in  the 
popular  language  of  superficial  exposition — and 
even  in  the  unguarded  and  playful  paradox  of 
their  authors,  intended  only  for  the  instructed 
eye — often  look  bizarre  enough. 

One  thing  is  very  notable,  that  it  is 


1 8  Presidential  Address 

closer  and  more  exact  knowledge  that 
has  led  to  the  kind  of  scientific  scepticism 
now  referred  to ;  and  that  the  simple  laws 
on  which  we  used  to  be  working  were  thus 
simple  and  discoverable  because  the  full 
complexity  of  existence  was  tempered  to 
our  ken  by  the  roughness  of  our  means  of 
observation. 

Kepler's  laws  are  not  accurately  true, 
and  if  he  had  had  before  him  all  the  data 
now  available  he  could  hardly  have  dis- 
covered them.  A  planet  does  not  really 
move  in  an  ellipse  but  in  a  kind  of  hypo- 
cycloid,  and  not  accurately  in  that  either. 

So  it  is  also  with  Boyle's  law,  and 
the  other  simple  laws  in  Physical  Chem- 
istry. Even  Van  der  Waals'  general- 
isation of  Boyle's  law  is  only  a  further 
approximation . 

In  most  parts  of  physics  simplicity  has 
sooner  or  later  to  give  place  to  complexity: 
though  certainly  I  urge  that  the  simple 
laws  were  true,  and  are  still  true,  as  far 
as  they  go,  their  inaccuracy  being  only 
detected  by  further  real  discovery.  The 
reason  they  are  departed  from  becomes 


Continuity  19 

known  to  us;  the  law  is  not  really  dis- 
obeyed, but  is  modified  through  the 
action  of  a  known  additional  cause. 
Hence  it  is  all  in  the  direction  of  progress. 
It  is  only  fair  to  quote  Poincare  again, 
now  that  I  am  able  in  the  main  to  agree 
with  him : 

Take  for  instance  the  laws  of  reflection. 
Fresnel  established  them  by  a  simple  and  at- 
tractive theory  which  experiment  seemed  to  con- 
firm. Subsequently,  more  accurate  researches 
have  shown  that  this  verification  was  but 
approximate ;  traces  or  elliptic  polarisation  were 
detected  elsewhere.  But  it  is  owing  to  the  first 
approximation  that  the  cause  of  these  anomalies 
was  found,  in  the  existence  of  a  transition  layer; 
and  all  the  essentials  of  Fresnel' s  theory  have 
remained.  We  cannot  help  reflecting  that  all 
these  relations  would  never  have  been  noted  if 
there  had  been  doubt  in  the  first  place  as  to  the 
complexity  of  the  objects  they  connect.  Long 
ago  it  was  said :  If  Tycho  had  had  instruments 
ten  times  as  precise,  we  would  never  have  had  a 
Kepler,  or  a  Newton,  or  Astronomy.  It  is  a  , 
misfortune  for  a  science  to  be  born  too  late,  when 
the  means  of  observation  have  become  too  per- 
fect. That  is  what  is  happening  at  this  moment 
with  respect  to  physical  chemistry:  the  founders 


20  Presidential  Address 

are  hampered  in  their  general  grasp  by  third 
and  fourth  decimal  places;  happily  they  are 
men  of  robust  faith.  As  we  get  to  know  the 
properties  of  matter  better  we  see  that  continuity 
reigns.  ...  It  would  be  difficult  to  just- 
ify [the  belief  in  continuity]  by  apodeictic 
reasoning,  but  without  it  all  science  would  be 
impossible. 

Here  he  touches  on  my  own  theme, 
Continuity;  and,  if  we  had  to  summarise 
the  main  trend  of  physical  controversy 
at  present,  I  feel  inclined  to  urge  that  it 
largely  turns  on  the  question  as  to  which 
way  ultimate  victory  lies  in  the  fight 
between  Continuity  and  Discontinuity. 

On  the  surface  of  nature  at  first  we 
see  discontinuity;  objects  detached  and 
countable.  Then  we  realise  the  air  and 
other  media,  and  so  emphasise  continuity 
and  flowing  quantities.  Then  we  detect 
atoms  and  numerical  properties,  and  dis- 
continuity once  more  makes  its  appear- 
ance. Then  we  invent  the  ether  and  are 
impressed  with  continuity  again.  But 
this  is  not  likely  to  be  the  end ;  and  what 
the  ultimate  end  will  be,  or  whether  there 


Continuity  21 

is  an  ultimate  end,  is  a  question  difficult 
to  answer. 

The  modern  tendency  is  to  emphasise 
the  discontinuous  or  atomic  character  of 
everything.  Matter  has  long  been  atomic, 
in  the  same  sense  as  Anthropology  is 
atomic;  the  unit  of  matter  is  the  atom, 
as  the  unit  of  humanity  is  the  individual. x 
Whether  men  or  women  or  children — 
they  can  be  counted  as  so  many  "  souls. " 
And  atoms  of  matter  can  be  counted  too. 

Certainly,  however,  there  is  an  illusion 
of  continuity.  We  recognise  it  in  the 
case  of  water.  It  appears  to  be  a  con- 
tinuous medium,  and  yet  it  is  certainly 
molecular.  It  is  made  continuous  again, 
in  a  sense,  by  the  ether  postulated  in  its 
pores,  for  the  ether  is  essentially  con- 
tinuous; though  Osborne  Reynolds,  it 
is  true,  invented  a  discontinuous  or 
granular  Ether,  on  the  analogy  of  the 
sea  shore.  The  sands  of  the  sea,  the 
hairs  of  the  head,  the  descendants  of  a 

1  In  his  recent  Canadian  Address,  Lord  Haldane  em- 
phasised the  national  and  social  continuity  of  the  human 
race  as  opposed  to  individual  discontinuity. 


22  Presidential  Address 

Patriarch,  are  typical  instances  of  nu- 
merable, or  rather  innumerable,  things. 
The  difficulty  of  enumerating  them  is 
not  that  there  is  nothing  to  count,  but 
merely  that  the  things  to  be  counted 
are  very  numerous.  So  are  the  atoms 
in  a  drop  of  water, — they  outnumber 
the  drops  in  an  Atlantic  Ocean, — and, 
during  the  briefest  time  of  stating  their 
number,  fifty  millions  or  so  may  have 
evaporated;  but  they  are  as  easy  to 
count  as  the  grains  of  sand  on  a  shore. 

The  process  of  counting  is  evidently 
a  process  applicable  to  discontinuities, 
i.  e.,  to  things  with  natural  units;  you 
can  count  apples  and  coins,  and  days  and 
years,  and  people  and  atoms.  To  apply 
number  to  a  continuum  you  must  first 
cut  it  up  into  artificial  units;  and  you 
are  always  left  with  incommensurable 
fractions.  Thus  only  is  it  that  you  can 
deal  numerically  with  such  continuous 
phenomena  as  the  warmth  of  a  room,  the 
speed  of  a  bird,  the  pull  of  a  rope,  or  the 
strength  of  a  current. 

But  how,  it  may  be  asked,  does  discon- 


Continuity  23 

tinuity  apply  to  number?  The  natural 
numbers,  i,  2,  3,  etc.,  are  discontinu- 
ous enough,  but  there  are  fractions  to 
fill  up  the  interstices;  how  do  we  know 
that  they  are  not  really  connected  by 
these  fractions,  and  so  made  continuous 
again? 

(By  number  I  always  mean  commensur- 
able number;  incommensurables  are  not 
numbers:  they  are  just  what  cannot  be 
expressed  in  numbers.  The  square  root 
of  2  is  not  a  number,  though  it  can  be 
readily  indicated  by  a  length.  Incom- 
mensurables are  usual  in  physics  and  are 
frequent  in  geometry;  the  conceptions  of 
geometry  are  essentially  continuous.  It 
is  clear,  as  Poincare  says,  that  "if  the 
points  whose  co-ordinates  are  commen- 
surable were  alone  regarded  as  real,  the 
in-circle  of  a  square  and  the  diagonal 
of  the  square  would  not  intersect,  since 
the  co-ordinates  of  the  points  of  inter- 
section are  incommensurable.") 

I  want  to  explain  how  commensurable 
fractions  do  not  connect  up  numbers,  nor 
remove  their  discontinuity  in  the  least. 


24  Presidential  Address 

The  divisions  on  a  foot  rule,  divided  as 
closely  as  you  please,  represent  commen- 
surable fractions,  but  they  represent  none 
of  the  length.  No  matter  how  numerous 
they  are,  all  the  length  lies  between  them; 
the  divisions  are  mere  partitions  and  have 
consumed  none  of  it ;  nor  do  they  connect 
up  with  each  other,  they  are  essentially 
discontinuous.  The  interspaces  are  in- 
finitely more  extensive  than  the  barriers 
which  partition  them  off  from  one  another ; 
they  are  like  a  row  of  compartments 
with  infinitely  thin  walls.  All  the  incom- 
mensurables  lie  in  the  interspaces;  the 
compartments  are  full  of  them,  and  they 
are  thus  infinitely  more  numerous  than 
the  numerically  expressible  magnitudes. 
Take  any  point  of  the  scale  at  random, 
that  point  will  certainly  lie  in  an  inter- 
space: it  will  not  lie  on  a  division,  for  the 
chances  are  infinity  to  I  against  it. 

Accordingly  incommensurable  quanti- 
ties are  the  rule  in  physics.  Decimals  do 
not  in  practice  terminate  or  circulate, 
in  other  words  vulgar  fractions  do  not 
accidentally  occur  in  any  measurements, 


Continuity  25 

for  this  would  mean  infinite  accuracy. 
We  proceed  to  as  many  places  of  decimals 
as  correspond  to  the  order  of  accuracy 
aimed  at. 

Whenever,  then,  a  commensurable  number 
is  really  associated  with  any  natural  phe- 
nomenon, there  is  necessarily  a  noteworthy 
circumstance  involved  in  the  fact,  and  it 
means  something  quite  definite  and  ulti- 
mately ascertainable.  Every  discontinuity 
that  can  be  detected  and  counted  is  an 
addition  to  knowledge.  It  not  only  means 
the  discovery  of  natural  units  instead  of 
being  dependent  on  artificial  ones,  but  it 
throws  light  also  on  the  nature  of  phe- 
nomena themselves. 

For  instance: 

The  ratio  between  the  velocity  of  light 
and  the  inverted  square  root  of  the  pro- 
duct of  the  electric  and  magnetic  con- 
stants was  discovered  by  Clerk  Maxwell 
to  be  i ;  and  a  new  volume  of  physics  was 
by  that  discovery  opened. 

Dalton  found  that  chemical  combina- 
tion occurred  between  quantities  of  dif- 
ferent substances  specified  by  certain 


26  Presidential  Address 

whole  or  fractional  numbers;  and  the 
atomic  theory  of  matter  sprang  into  sub- 
stantial though  at  first  infantile  existence. 

The  hypothesis  of  Prout,  which  in  some 
modified  form  seems  likely  to  be  sub- 
stantiated, is  that  all  atomic  weights  are 
commensurable  numbers;  in  which  case 
there  must  be  a  natural  fundamental 
unit  underlying,  and  in  definite  groups 
composing,  the  atoms  of  every  form  of 
matter. 

The  small  number  of  degrees  of  freedom 
of  a  molecule,  and  the  subdivision  of  its 
total  energy  into  equal  parts  correspond- 
ing thereto,  is  a  theme  not  indeed  without 
difficulty  but  full  of  importance.  It  is 
responsible  for  the  suggestion  that  energy 
too  may  be  atomic! 

Mendelejeff's  series  again,  or  the  detec- 
tion of  a  natural  grouping  of  atomic 
weights  in  families  of  seven,  is  another 
example  of  the  significance  of  number. 

Electricity  was  found  by  Faraday  to  be 
numerically  connected  with  quantity  of 
matter ;  and  the  atom  of  electricity  began 
its  hesitating  but  now  brilliant  career. 


Continuity  27 

Electricity  itself — i.  e.,  electric  charge — 
strangely  enough  has  proved  itself  to  be 
atomic.  There'  is  a  natural  unit  of 
electric  charge,  as  suspected  by  Faraday 
and  Maxwell  and  named  by  Johnstone 
Stoney.  Some  of  the  electron's  visible 
effects  were  studied  by  Crookes  in  a 
vacuum;  and  its  weighing  and  measuring 
by  J.  J.  Thomson  were  announced  to  the 
British  Association  meeting  at  Dover  in 
1899 — a  striking  prelude  to  the  twentieth 
century. 

An  electron  is  the  natural  unit  of 
negative  electricity,  and  it  may  not  be 
long  before  the  natural  unit  of  positive 
electricity  is  found  too.  But  concerning 
the  nature  of  the  positive  unit  there  is  at 
present  some  division  into  opposite  camps. 
One  school  prefers  to  regard  the  unit  of 
positive  electricity  as  a  homogeneous 
sphere,  the  size  of  an  atom,  in  which  elec- 
trons revolve  in  simple  harmonic  orbits 
and  constitute  nearly  the  whole  effective 
mass.  Another  school,  while  appreci- 
ating the  simplicity  and  ingenuity  and 
beauty  of  the  details  of  this  conception, 


28  Presidential  Address 

and  the  skill  with  which  it  has  been 
worked  out,  yet  thinks  the  evidence  more 
in  favour  of  a  minute '  central  positive 
nucleus,  or  nucleus-group,  of  practically 
atomic  mass;  with  electrons,  larger — i.  e., 
less  concentrated — and  therefore  less 
massive  than  itself,  revolving  round  it  in 
astronomical  orbits.  While  from  yet  an- 
other point  of  view  it  is  insisted  that 
positive  and  negative  electrons  can  only 
differ  skew-symmetrically,  one  being  like 
the  image  of  the  other  in  a  mirror,  and 
that  the  mode  in  which  they  are  grouped 
to  form  an  atom  remains  for  future  dis- 
covery. But  no  one  doubts  that  elec- 
tricity is  ultimately  atomic. 

Even  magnetism  has  been  suspected 
of  being  atomic,  and  its  hypothetical  unit 
has  been  named  in  advance  the  magneton: 
but  I  confess  that  here  I  have  not  been 
shaken  out  of  the  conservative  view. 

We  may  express  all  this  as  an  invasion 
of  number  into  unexpected  regions. 

Biology  may  be  said  to  be  becoming 
atomic.  It  has  long  had  natural  units 
in  the  shape  of  cells  and  nuclei,  and  some 


Continuity  29 

discontinuity  represented  by  body -bound- 
aries and  cell-walls;  but  now,  in  its  laws 
of  heredity  as  studied  by  Mendel,  number 
and  discontinuity  are  strikingly  apparent 
among  the  reproductive  cells,  and  the 
varieties  of  offspring  admit  of  numerical 
specification  and  prediction  to  a  surpris- 
ing extent;  while  modification  by  con- 
tinuous variation,  which  seemed  to  be  of 
the  essence  of  Darwinism,  gives  place  to, 
or  at  least  is  accompanied  by,  mutation, 
with  finite  and  considerable  and  in  ap- 
pearance discontinuous  change.  So  far 
from  Nature  not  making  jumps,  it  be- 
comes doubtful  if  she  does  anything  else. 
Her  hitherto  placid  course,  more  closely 
examined,  is  beginning  to  look  like  a  kind 
of  steeplechase. 

Yet  undoubtedly  Continuity  is  the 
backbone  of  evolution,  as  taught  by  all 
biologists — no  artificial  boundaries  or  de- 
marcations between  species — a  continuous 
chain  of  heredity  from  far  below  the 
amoeba  up  to  man.  Actual  continuity 
of  undying  germ-plasm,  running  through 
all  generations,  is  taught  likewise;  though 


3Q  Presidential  Address 

a  strange  discontinuity  between  this 
persistent  element  and  its  successive 
accessory  body-plasms — a  discontinuity 
which  would  convert  individual  organisms 
into  mere  temporary  accretions  or  excre- 
tions, with  no  power  of  influencing  or 
conveying  experience  to  their  generating 
cells — is  advocated  by  one  school. 

Discontinuity  does  not  fail  to  exercise 
fascination  even  in  pure  Mathematics. 
Curves  are  invented  which  have  no 
tangent  or  differential  coefficient,  curves 
which  consist  of  a  succession  of  dots  or  of 
twists ;  and  the  theory  of  commensurable 
numbers  seems  to  be  exerting  a  dominance 
over  philosophic  mathematical  thought 
as  well  as  over  physical  problems. 

And  not  only  these  fairly  accepted 
results  are  prominent,  but  some  more 
difficult  and  unexpected  theses  in  the  same 
direction  are  being  propounded,  and  the 
atomic  character  of  Energy  is  advocated. 
We  had  hoped  to  be  honoured  by  the 
presence  of  Professor  Planck,  whose 
theory  of  the  quantum,  or  indivisible  unit 
or  atom  of  energy,  excites  the  greatest 


Continuity  31 

interest,  and  by  some  is  thought  to  hold 
the  field.1 

Then  again  Radiation  is  showing  signs 
of  becoming  atomic  or  discontinuous. 
The  corpuscular  theory  of  radiation  is 
by  no  means  so  dead  as  in  my  youth  we 
thought  it  was.  Some  radiation  is  cer- 
tainly corpuscular,  and  even  the  etherial 
kind  shows  indications,  which  may  be 
misleading,  that  it  is  spotty,  or  locally 
concentrated  into  points,  as  if  the  wave- 
front  consisted  of  detached  specks  or 
patches;  or,  as  J.  J.  Thomson  says,  "the 
wave-front  must  be  more  analogous  to 
bright  specks  on  a  dark  ground  than  to  a 
uniformly  illuminated  surface, "  thus  sug- 
gesting that  the  Ether  may  be  fibrous  in 
structure,  and  that  a  wave  runs  along 
lines  of  electric  force;  as  the  genius  of 
Faraday  surmised  might  be  possible,  in 
his  "Thoughts  on  Ray  Vibrations. "  In- 
deed Newton  guessed  something  of  the 
same  kind,  I  fancy,  when  he  superposed 
ether-pulses  on  his  corpuscles. 

Whatever  be  the  truth  in  this  matter,  a 

1  Se;e  page  37. 


32  Presidential  Address 

discussion  on  Radiation,  of  extreme 
weight  and  interest,  though  likewise  of 
great  profundity  and  technicality,  is  ex- 
pected on  Friday  in  Section  A.  We  wel- 
come Professor  Lorentz,  Dr.  Arrhenius, 
Professor  Jeans,  Professor  Pringsheim, 
and  others,  some  of  whom  have  been 
specially  invited  to  England  because  of 
the  important  contributions  which  they 
have  made  to  the  subject-matter  of  this 
discussion. 

Why  is  so  much  importance  attached 
to  Radiation?  Because  it  is  the  best- 
known  and  longest-studied  link  between 
matter  and  ether,  and  the  only  property 
we  are  acquainted  with  that  affects  the 
unmodified  great  mass  of  ether  alone. 
Electricity  and  magnetism  are  associated 
with  the  modifications  or  singularities 
called  electrons.  Heat  and  sound  are 
connected  still  more  directly  with  matter. 
Radiation,  however,  though  excited  by  an 
accelerated  electron,  is  subsequently  let 
loose  in  the  ether  of  space,  and  travels  as 
a  definite  thing  at  a  measurable  and 
constant  pace — a  pace  independent  of 


Continuity  33 

everything  so  long  as  the  ether  is  free, 
unmodified  and  unloaded  by  matter. 
Hence  radiation  has  much  to  teach  us, 
and  we  have  much  to  learn  concerning  its 
nature. 

How  far  can  the  analogy  of  granular, 
corpuscular,  countable,  atomic,  or  dis- 
continuous things  be  pressed?  There 
are  those  who  think  it  can  be  pressed  very 
far.  But  to  avoid  misunderstanding  let 
me  state,  for  what  it  may  be  worth,  that 
I  myself  am  an  upholder  of  ultimate  Con- 
tinuity, and  a  fervent  believer  in  the 
Ether  of  Space. 

We  have  already  learnt  something 
about  the  ether;  and  although  there  may 
be  almost  as  many  varieties  of  opinion 
as  there  are  people  qualified  to  form  one, 
in  my  view  we  have  learnt  as  follows: 

The  Ether  is  the  universal  connecting 
medium  which  binds  the  universe  to- 
gether, and  makes  it  a  coherent  whole 
instead  of  a  chaotic  collection  of  inde- 
pendent isolated  fragments.  It  is  the 
vehicle  of  transmission  of  all  manner  of 
force,  from  gravitation  down  to  cohesion 


34  Presidential  Address 

and  chemical  affinity;  it  is  therefore  the 
storehouse  of  potential  energy. 

Matter  moves,  but  Ether  is  strained. 

What  we  call  elasticity  of  matter  is 
only  the  result  of  an  alteration  of  con- 
figuration due  to  movement  and  read- 
justment of  particles,  but  all  the  strain 
and  stress  are  in  the  ether.  The  ether 
itself  does  not  move,  that  is  to  say  it  does 
not  move  in  the  sense  of  locomotion, 
though  it  is  probably  in  a  violent  state 
of  rotational  or  turbulent  motion  in  its 
smallest  parts;  and  to  that  motion  its 
exceeding  rigidity  is  due. 

As  to  its  density,  it  must  be  far  greater 
than  that  of  any  form  of  matter,  millions 
of  times  denser  than  lead  or  platinum. 
Yet  matter  moves  through  it  with  per- 
fect freedom,  without  any  friction  or 
viscosity.  There  is  nothing  paradoxical 
in  this:  viscosity  is  not  a  function  of 
density;  the  two  are  not  necessarily 
connected.  When  a  solid  moves  through 
an  alien  fluid  it  is  true  that  it  acquires 
a  spurious  or  apparent  extra  inertia 
from  the  fluid  it  displaces;  but,  in  the 


Continuity  35 

case  of  matter  and  ether,  not  only  is  even 
the  densest  matter  excessively  porous 
and  discontinuous,  with  vast  interspaces 
in  and  among  the  atoms,  but  the  consti- 
tution of  matter  is  such  that  there  appears 
to  be  no  displacement  in  the  ordinary 
sense  at  all;  the  ether  is  itself  so  modified 
as  to  constitute  the  matter  in  some  way. 
Of  course  that  portion  moves,  its  inertia 
is  what  we  observe,  and  its  amount  de- 
pends on  the  potential  energy  in  its 
associated  electric  field,  but  the  motion 
is  not  like  that  of  a  foreign  body,  it 
is  that  of  some  inherent  and  merely 
individualised  portion  of  the  stuff  itself. 
Certain  it  is  that  the  ether  exhibits  no 
trace  of  viscosity.1 

Matter  in  motion,  Ether  under  strain, 
constitute  the  fundamental  concrete 
things  we  have  to  do  with  in  physics. 
The  first  pair  represent  kinetic  energy, 
the  second  potential  energy;  and  all  the 

1  For  details  of  my  experiment  on  this  subject  see  Phil. 
Trans.  Roy.Soc.  for  1893  and  1897;  or  a  very  abbreviated 
reference  to  it,  and  to  the  other  matters  above-mentioned, 
in  my  small  book  The  Ether  of  Space. 


36  Presidential  Address 

activities  of  the  material  universe  are 
represented  by  alternations  from  one 
of  these  forms  to  the  other. 

Whenever  this  transference  and  trans- 
formation of  energy  occur,  work  is  done, 
and  some  effect  is  produced,  but  the 
energy  is  never  diminished  in  quantity: 
it  is  merely  passed  on  from  one  body  to 
another,  always  from  ether  to  matter 
or  vice  versa, — except  in  the  case  of 
radiation,  which  simulates  matter, — and 
from  one  form  to  another. 

The  forms  of  energy  can  be  classified 
as  either  a  translation,  a  rotation,  or  a 
vibration,  of  pieces  of  matter  of  different 
sizes,  from  stars  and  planets  down  to 
atoms  and  electrons;  or  else  an  etherial 
strain  which  in  various  different  ways  is 
manifested  by  the  behaviour  of  such 
masses  of  matter  as  appeal  to  our  senses. J 

Some  of  the  facts  responsible  for  the 
suggestion  that  energy  is  atomic  seem  to 
me  to  depend  on  the  discontinuous  nature 
of  the  structure  of  a  material  atom,  and 

1  See,  in  the  Philosophical  Magazine  for  October,  1879, 
my  article  on  a  Classification  of  the  forms  of  energy. 


Continuity  37 

on  the  high  velocity  of  its  constituent 
particles.  The  apparently  discontinu- 
ous emission  of  radiation  is,  I  believe, 
due  to  features  in  the  real  discontinuity 
of  matter.  Disturbances  inside  an  atom 
appear  to  be  essentially  catastrophic; 
a  portion  is  liable  to  be  ejected  with 
violence.  There  appears  to  be  a  critical 
velocity  below  which  ejection  does  not 
take  place;  and,  when  it  does,  there  also 
occurs  a  sudden  rearrangement  of  parts 
which  is  presumably  responsible  for  some 
perceptible  etherial  radiation.  Hence  it 
is,  I  suppose,  that  radiation  comes  off 
in  gushes  or  bursts ;  and  hence  it  appears 
to  consist  of  indivisible  units.  The 
occasional  phenomenon  of  new  stars,  as 
compared  with  the  steady  orbital  mo- 
tion of  the  millions  of  recognised  bodies, 
may  be  suggested  as  an  astronomical 
analogue. 

The  hypothesis  of  quanta  was  devised 
to  reconcile  the  law  that  the  energy  of  a 
group  of  colliding  molecules  must  in  the 
long  run  be  equally  shared  among  all 
their  degrees  of  freedom,  with  the  ob- 


33  Presidential  Address 

served  fact  that  the  energy  is  really  shared 
into  only  a  small  number  of  equal  parts. 
For  if  vibration-possibilities  have  to  be 
taken  into  account,  the  number  of  de- 
grees of  molecular  freedom  must  be  very 
large,  and  energy  shared  among  them 
ought  soon  to  be  all  frittered  away; 
whereas  it  is  not.  Hence  the  idea  is 
suggested  that  minor  degrees  of  freedom 
are  initially  excluded  from  sharing  the 
energy,  because  they  cannot  be  supplied 
with  less  than  one  atom  of  it. 

I  should  prefer  to  express  the  fact  by 
saying  that  the  ordinary  encounters  of 
molecules  are  not  of  a  kind  able  to  excite 
atomic  vibrations,  or  in  any  way  to  dis- 
turb the  ether.  Spectroscopic  or  lumin- 
ous vibrations  of  an  atom  are  excited  only 
by  an  exceptionally  violent  kind  of  col- 
lision, which  may  be  spoken  of  as  chemi- 
cal clash;  the  ordinary  molecular  orbital 
encounters,  always  going  on  at  the  rate 
of  millions  a  second,  are  ineffective  in 
that  respect,  except  in  the  case  of  phos- 
phorescent or  luminescent  substances. 
That  common  molecular  deflexions  are 


Continuity  39 

ineffective  is  certain,  else  all  the  energy 
would  be  dissipated  or  transferred  from 
matter  into  the  ether ;  and  the  reasonable- 
ness of  their  radiative  inefficiency  is 
not  far  to  seek,  when  we  consider  the 
comparatively  leisurely  character  of 
molecular  movements,  at  speeds  com- 
parable with  the  velocity  of  sound. 
Admittedly,  however,  the  effective 
rigidity  of  molecules  must  be  complete, 
otherwise  the  sharing  of  energy  must 
ultimately  occur.  They  do  not  seem 
able  to  be  set  vibrating  by  anything  less 
than  a  certain  minimum  stimulus;  and 
that  is  the  basis  for  the  theory  of  quanta. 
Quantitative  applications  of  Planck's 
theory,  to  elucidate  the  otherwise  shaky 
stability  of  the  astronomically  consti- 
tuted atom,  have  been  made;  and  the 
agreement  between  results  so  calculated 
and  those  observed,  including  a  deter- 
mination of  series  of  spectrum  lines,  is 
very  remarkable.  One  of  the  latest  con- 
tributions to  this  subject  is  a  paper  by 
Dr.  Bohr  in  the  Philosophical  Maga- 
zine for  July,  1913. 


40  Presidential  Address 

To  show  that  I  am  not  exaggerating 
the  modern  tendency  towards  discon- 
tinuity, I  quote,  from  M.  Poincare's 
Dernieres  Pensees,  a  proposition  which 
he  announces  in  italics  as  representing  a 
form  of  Professor  Planck's  view  of  which 
he  apparently  approves: 

A  physical  system  is  susceptible  of  a  finite 
number  only  of  distinct  conditions;  it  jumps 
from  one  of  these  conditions  to  another  without 
passing  through  a  continuous  series  of  inter- 
mediate conditions. 

Also  this  from  Sir  Joseph  Larmor's 
Preface  to  Poincare's  Science  and 
Hypothesis: 

Still  more  recently  it  has  been  found  that 
the  good  Bishop  Berkeley's  logical  jibes  against 
the  Newtonian  ideas  of  fluxions  and  limiting 
ratios  cannot  be  adequately  appeased  in  the 
rigorous  mathematical  conscience,  until  our 
apparent  continuities  are  resolved  mentally 
into  discrete  aggregates  which  we  only  partially 
apprehend.  The  irresistible  impulse  to  atomise 
everything  thus  proves  to  be  not  merely  a  dis- 
ease of  the  physicist:  a  deeper  origin,  in  the 
nature  of  knowledge  itself,  is  suggested. 


Continuity  41 

One  very  valid  excuse  for  this  preva- 
lent attitude  is  the  astonishing  progress 
that  has  been  made  in  actually  seeing  or 
almost  seeing  the  molecules,  and  study- 
ing their  arrangement  and  distribution. 

The  laws  of  gases  have  been  found  to 
apply  to  emulsions  and  to  fine  powders  in 
suspension,  of  which  the  Brownian  move- 
ment has  long  been  known.  This  move- 
ment is  caused  by  the  orthodox  molecular 
bombardment,  and  its  average  amplitude 
exactly  represents  the  theoretical  mean 
free  path  calculated  from  the  "molecular 
weight"  of  the  relatively  gigantic  particles. 
The  behaviour  of  these  microscopically 
visible  masses  corresponds  closely  and 
quantitatively  with  what  could  be  pre- 
dicted for  them  as  fearfully  heavy  atoms, 
on  the  kinetic  theory  of  gases;  they  may 
indeed  be  said  to  constitute  a  gas  with  a 
gram-molecule  as  high  as  200,000  tons; 
and,  what  is  rather  important  as  well  as 
interesting,  they  tend  visibly  to  verify 
the  law  of  equipartition  of  energy  even 
in  so  extreme  a  case,  when  that  law 
is  properly  stated  and  applied. 


42  Presidential  Address 

Still  more  remarkable — the  application 
of  X-rays  to  display  the  arrangement  of 
molecules  in  crystals,  and  ultimately  the 
arrangement  of  atoms  in  molecules,  as 
initiated  by  Professor  Laue  with  Drs. 
Friedrich  and  Knipping,  and  continued 
by  Professor  Bragg  and  his  son  and  by 
Dr.  Tutton,  constitute  a  series  of  re- 
searches of  high  interest  and  promise. 
By  this  means  many  of  the  theoretical 
anticipations  of  our  countryman,  Mr. 
William  Barlow,  and — working  with  him 
— Professor  Pope,  as  well  as  of  those  dis- 
tinguished crystallographers  von  Groth 
and  von  Fedorow,  have  been  confirmed 
in  a  striking  way.  These  brilliant  re- 
searches, which  seem  likely  to  constitute 
a  branch  of  Physics  in  themselves,  and 
which  are  being  continued  by  Messrs. 
Moseley  and  C.  G.  Darwin,  and  by  Mr. 
Keene  and  others,  may  be  called  an  apo- 
theosis of  the  atomic  theory  of  matter. 

One  other  controversial  topic  I  shall 
touch  upon  in  the  domain  of  physics, 
though  I  shall  touch  upon  it  lightly  for 
it  is  not  a  matter  for  easy  reference  as 


Continuity  43 

yet.  If  the  "Principle  of  Relativity"  in 
an  extreme  sense  establishes  itself,  it 
seems  as  if  even  Time  would  become  dis- 
continuous and  be  supplied  in  atoms,  as 
money  is  doled  out  in  pence  or  centimes 
instead  of  continuously; — in  which  case 
our  customary  existence  will  turn  out  to 
be  no  more  really  continuous  than  the 
events  on  a  kinematograph  screen; — 
while  that  great  agent  of  continuity,  the 
Ether  of  Space,  will  be  relegated  to  the 
museum  of  historical  curiosities. 

In  that  case  differential  equations 
will  cease  to  represent  the  facts  of  nature, 
they  will  have  to  be  replaced  by  Finite 
Differences,  and  the  most  fundamen- 
tal revolution  since  Newton  will  be 
inaugurated. 

Now  in  all  the  debatable  matters  of 
which  I  have  indicated  possibilities  I 
want  to  urge  a  conservative  attitude.  I 
accept  the  new  experimental  results  on 
which  some  of  these  theories — such  as  the 
Principle  of  Relativity — are  based,  and 
am  profoundly  interested  in  them,  but 
I  do  not  feel  that  they  are  so  revolution- 


44  Presidential  Address 

ary  as  their  propounders  think.  I  see  a 
way  to  retain  the  old  and  yet  embrace 
the  new,  and  I  urge  moderation  in  the 
uprooting  and  removal  of  landmarks. 

And  of  these  the  chief  is  Continuity. 
I  cannot  imagine  the  exertion  of  mechan- 
ical force  across  empty  space,  no  matter 
how  minute;  a  continuous  medium  seems 
to  me  essential.  I  cannot  admit  dis- 
continuity in  either  Space  or  Time,  nor 
can  I  imagine  any  sort  of  experiment 
which  would  justify  such  a  hypothesis. 
For  surely  we  must  realise  that  we  know 
nothing  experimental  of  either  space  or 
time,  we  cannot  modify  them  in  any 
way.  We  make  experiments  on  bodies, 
and  only  on  bodies,  using  "body*'  as  an 
exceedingly  general  term. 

We  have  no  reason  to  postulate  any- 
thing but  continuity  for  space  and  time. 
We  cut  them  up  into  conventional  units 
for  convenience  sake,  and  those  units 
we  can  count;  but  there  is  really  nothing 
atomic  or  countable  about  the  things 
themselves.  We  can  count  the  rotations 
of  the  earth,  or  the  revolutions  of  an 


Continuity  45 

electron,  or  the  vibrations  of  a  pendulum 
or  the  waves  of  light.  All  these  are  con- 
crete and  tractable  physical  entities;  but 
space  and  time  are  ultimate  data,  ab- 
stractions based  on  experience.  We  know 
them  through  motion,  and  through 
motion  only,  and  motion  is  essentially 
continuous.  We  ought  clearly  to  dis- 
criminate between  things  themselves  and 
our  mode  of  measuring  them.  Our 
measures  and  perceptions  may  be  af- 
fected by  all  manner  of  incidental  and 
trivial  causes,  and  we  may  get  confused 
or  hampered  by  our  own  movement; 
but  there  need  be  no  such  complication 
in  things  themselves,  any  more  than  a 
landscape  is  distorted  by  looking  at  it 
through  an  irregular  window-pane  or 
from  a  travelling  coach.  It  is  an  ancient 
and  discarded  fable  that  complications 
introduced  by  the  motion  of  an  observer 
are  real  complications  belonging  to  the 
outer  universe. 

Very  well,  then,  what  about  the  Ether; 
is  that  in  the  same  predicament?  Is  that 
an  abstraction,  or  a  mere  convention,  or 


46  Presidential  Address 

is  it  a  concrete  physical  entity  on  which 
we  can  experiment? 

Now  it  has  to  be  freely  admitted  that 
it  is  exceedingly  difficult  to  make  experi- 
ments on  the  ether.  It  does  not  appeal 
to  sense,  and  we  know  no  means  of  getting 
hold  of  it.  The  one  thing  we  know 
metrical  about  it  is  the  velocity  with 
which  it  can  transmit  transverse  waves. 
That  is  clear  and  definite,  and  thereby 
to  my  judgment  it  proves  itself  a  physical 
agent;  not  indeed  tangible  or  sensible, 
but  yet  concretely  real. 

But  it  does  elude  our  laboratory  grasp. 
If  we  rapidly  move  matter  through  it, 
hoping  to  grip  it  and  move  it  too,  we 
fail:  there  is  no  mechanical  connection. 
And  even  if  we  experiment  on  light  we 
fail  too.  So  long  as  transparent  matter 
is  moving  relatively  to  us,  light  can  be 
affected  inside  that  matter;  but  when 
matter  is  relatively  stationary  to  matter 
nothing  observable  takes  place,  however 
fast  things  may  be  moving,  so  long  as 
they  move  together. 

Hence  arises  the  idea  that  motion  with 


Continuity  47 

respect  to  Ether  is  meaningless:  and  the 
fact  that  only  relative  motion  of  pieces 
of  matter  with  respect  to  each  other  has 
so  far  been  observed  is  the  foundation  of 
the  Principle  of  Relativity.  It  sounds 
simple  enough  as  thus  stated,  but  in  its 
developments  it  is  an  ingenious  and  com- 
plicated doctrine  embodying  surprising 
consequences  which  have  been  worked 
out  by  Professor  Einstein  and  his  disciples 
with  consummate  ingenuity. 

What  have  I  to  urge  against  it?  Well, 
in  the  first  place,  it  is  only  in  accordance 
with  common  sense  that  no  effect  of 
the  first  order  can  be  observed  with- 
out relative  motion  of  matter.  An 
Ether-stream  through  our  laboratories  is 
optically  and  electrically  undetectable, 
at  least  as  regards  first-order  observa- 
tion; this  is  clearly  explained  for  general 
readers  in  my  book  The  Ether  of 
Space,  Chapter  TV.  But  the  Principle  of 
Relativity  says  more  than  that,  it  says 
that  no  effect  of  any  order  of  magnitude 
can  ever  be  observed,  without  the  rela- 
tive motion  of  matter. 


48  Presidential  Address 

The  truth  underlying  this  doctrine  is 
that  absolute  motion  without  reference 
to  anything  is  unmeaning.  But  the 
narrowing  down  of  "  any  thing"  to  mean 
any  piece  of  matter  is  illegitimate.  The 
nearest  approach  to  absolute  motion 
that  we  can  physically  imagine  is  motion 
through  or  with  respect  to  the  Ether  of 
Space.  It  is  natural  to  assume  that  the 
Ether  is  on  the  whole  stationary,  and  to 
use  it  as  a  standard  of  rest;  in  that  sense 
motion  with  reference  to  it  may  be  called 
absolute,  but  in  no  other  sense. 

The  Principle  of  Relativity  claims  that 
we  can  never  ascertain  such  motion:  in 
other  words  it  practically  or  pragmati- 
cally denies  the  existence  of  the  Ether. 
Every  one  of  our  scientifically  observed 
motions,  it  says,  are  of  the  same  nature 
as  our  popularly  observed  ones,  viz., 
motion  of  pieces  of  matter  relatively  to 
each  other;  and  that  is  all  that  we  can 
ever  know.  Everything  goes  on — says 
the  Principle  of  Relativity — as  if  the 
Ether  did  not  exist. 

Now  the  facts  are  that  no  motion  with 


Continuity  49 

reference  to  the  ether  alone  has  ever  yet 
been  observed:  there  are  always  curious 
compensating  effects  which  just  cancel 
out  the  movement-terms  and  destroy  or 
effectively  mask  any  phenomenon  that 
might  otherwise  be  expected.  When 
matter  moves  past  matter  observation 
can  be  made;  but,  even  so,  no  consequent 
locomotion  of  ether,  outside  the  actually 
moving  particles,  can  be  detected. 

(It  is  sometimes  urged  that  rotation 
is  a  kind  of  absolute  motion  that  can  be 
detected,  even  in  isolation.  It  can  so  be 
detected,  as  Newton  pointed  out;  but 
in  cases  of  rotation  matter  on  one  side 
the  axis  is  moving  in  the  opposite  direc- 
tion to  matter  on  the  other  side  of  the 
axis;  hence  rotation  involves  relative 
material  motion,  and  therefore  can  be 
observed.) 

To  detect  motion  through  ether  we 
must  use  an  etherial  process.  We  may 
use  radiation,  and  try  to  compare 
the  speeds  of  light  along  or  across  the 
motion;  or  we  might  try  to  measure  the 
speed,  first  with  the  motion  and  then 


50  Presidential  Address 

against  it.  But  how  are  we  to  make  the 
comparison?  If  the  time  of  emission 
from  a  distant  source  is  given  by  a  dis- 
tant clock,  that  clock  must  be  observed 
through  a  telescope,  that  is  by  a  beam  of 
light;  which  is  plainly  a  compensating 
process.  Or  the  light  from  a  neighbouring 
source  can  be  sent  back  to  us  by  a  distant 
mirror ;  when  again  there  will  be  compen- 
sation. Or  the  starting  of  light  from  a 
distant  terrestrial  source  may  be  tele- 
graphed to  us,  either  with  a  wire  or  with- 
out; but  it  is  the  ether  that  conveys  the 
message  in  either  case,  so  again  there 
will  be  compensation.  Electricity,  Mag- 
netism, and  Light,  are  all  effects  of  the 
ether. 

Use  Cohesion,  then;  have  a  rod  stretch- 
ing from  one  place  to  another,  and 
measure  that.  But  cohesion  is  trans- 
mitted by  the  ether  too,  if,  as  believed, 
it  is  the  universal  binding  medium. 
Compensation  is  likely;  compensation 
can,  on  the  electrical  theory  of  matter, 
be  predicted. 

Use   some   action   not   dependent   on 


Continuity  51 

Ether,  then.     Very  well,  where  shall  we 
find  it? 

To  illustrate  the  difficulty  I  will  quote 
a  sentence  from  Sir  Joseph  Larmor's 
paper  before  the  International  Congress 
of  Mathematicians  at  Cambridge  last 
year. 

If  it  is  correct  to  say  with  Maxwell  that  all 
radiation  is  an  electrodynamic  phenomenon, 
it  is  equally  correct  to  say  with  him  that  all 
electrodynamic  relations  between  material  bod- 
ies are  established  by  the  operation,  on  the 
molecules  of  those  bodies,  of  fields  of  force  which 
are  propagated  in  free  space  as  radiation  and  in 
accordance  with  the  laws  of  radiation,  from  one 
body  to  the  other. 

The  fact  is  we  are  living  in  an  epoch 
of  some  very  comprehensive  generalisa- 
tions. The  physical  discovery  of  the 
twentieth  century,  so  far,  is  the  Electrical 
Theory  of  Matter.  This  is  the  great  new 
theory  of  our  time;  it  was  referred  to, 
in  its  philosophical  aspect,  by  Mr.  Bal- 
four  in  his  Presidential  Address  at  Cam- 
bridge in  1904.  We  are  too  near  to  it  to 
be  able  to  contemplate  it  properly;  it 


52  Presidential  Address 

has  still  to  establish  itself  and  to  develop 
in  detail,  but  I  anticipate  that  in  some 
form  or  other  it  will  prove  true. x 

Here  is  a  briefest  possible  summary  of 
the  first  chapter  (so  to  speak)  of  the 
Electrical  Theory  of  Matter. 

(1)  Atoms  of  Matter  are  composed  of  elec- 
trons,—  of  positive  and  negative  electric 
charges. 

(2)  Atoms  are  bound  together  into  molecules 
by  chemical  affinity  which  is  intense  elec- 
trical attraction  at  ultra-minute  distances. 

(3)  Molecules  are  held  together  by  cohesion, 
which  I  for  one  regard  as  residual  or  differ- 
ential chemical  affinity  over  molecular  dis- 
tances. 

(4)  Magnetism  is  due  to  the  locomotion  of 
electrons.      There  is  no   magnetism  with- 
out an  electric  current,  atomic  or  otherwise. 
There    is   no    electric  current    without    a 
moving  electron. 

(5)  Radiation  is  generated  by  every  accel- 
erated electron,  in  amount  proportional  to 
the  square  of  its  acceleration;  and  there  is 
no  other  kind  of  radiation,  except  indeed 

1  For  a  general  introductory  account  of  the  electrical 
theory  of  matter  my  Romanes  lecture  for  1903  (Claren- 
don Press)  may  be  referred  to. 


Continuity  53 

a  corpuscular  kind;  but  this  depends  on 
the  velocity  of  electrons,  and  therefore 
again  can  only  be  generated  by  their  accel- 
eration. 

The  theory  is  bound  to  have  curious 
consequences;  and  already  it  has  con- 
tributed to  some  of  the  uprooting  and 
uncertainty  that  I  speak  of.  For,  if  it 
be  true,  every  material  interaction  will 
be  electrical,  i.  e.,  etherial;  and  hence 
arises  our  difficulty.  Every  kind  of 
force  is  transmitted  by  the  ether,  and 
hence,  so  long  as  all  our  apparatus  is 
travelling  together  at  one  and  the  same 
pace,  we  have  no  chance  of  detecting  the 
motion.  That  is  the  strength  of  the 
Principle  of  Relativity.  The  changes  are 
not  zero,  but  they  cancel  each  other  out  of 
observation. 

Many  forms  of  statement  of  the 
famous  Michelson-Morley  experiment 
are  misleading.  It  is  said  to  prove  that 
the  time  taken  by  light  to  go  with  the 
ether-stream  is  the  same  as  that  taken 
to  go  against  or  across  it.  It  does  not 
show  that.  What  it  shows  is  that  the 


54  Presidential  Address 

time  taken  by  light  to  travel  to  and  fro 
on  a  measured  interval  fixed  on  a  rigid 
block  of  matter  is  independent  of  the 
aspect  of  that  block  with  respect  to  any 
motion  of  the  earth  through  space.  A 
definite  and  most  interesting  result:  but 
it  may  be,  and  often  is,  interpreted 
loosely  and  too  widely. 

It  is  interpreted  too  widely,  as  I  think, 
when  Professor  Einstein  goes  on  to  as- 
sume that  no  non-relative  motion  of 
matter  can  be  ever  observed  even  when 
light  is  brought  into  consideration.  The 
relation  of  light  to  matter  is  very  curious. 
The  wave  front  of  a  progressive  wave 
simulates  many  of  the  properties  of 
matter.  It  has  energy,  it  has  momentum, 
it  exerts  force,  it  sustains  reaction.  It 
has  been  described  as  a  portion  of  the 
mass  of  a  radiating  body, — which  gives 
it  a  curiously  and  unexpectedly  corpuscu- 
lar ' '  feel. ' '  But  it  has  a  definite  velocity. 
Its  velocity  in  space  relative  to  the  ether 
is  an  absolute  constant  independent  of 
the  motion  of  the  source.  This  would 
not  be  true  for  corpuscular  light. 


Continuity  55 

Hence  I  hold  that  here  is  something 
with  which  our  own  motion  may  theoreti- 
cally be  compared;  and  I  predict  that 
our  motion  through  the  ether  will  some 
day  be  detected  by  help  of  this  very 
fact, — by  comparing  our  speed  with  that 
of  light:  though  the  old  astronomical 
aberration,  which  seemed  to  make  the 
comparison  easy,  failed  to  do  so  quite 
simply,  because  it  is  complicated  by  the 
necessity  of  observing  the  position  of  a 
distant  source,  in  relation  to  which  the 
earth  is  moving.  If  the  source  and 
observer  are  moving  together  there  is 
no  possibility  of  observing  aberration. 
Nevertheless  I  maintain  that  when  mat- 
ter is  moving  near  a  beam  of  light  we 
may  be  able  to  detect  the  motion.  For 
the  velocity  of  light  in  space  is  no  func- 
tion of  the  velocity  of  the  source,  nor  of 
matter  near  it;  it  is  quite  unaffected 
by  motion  of  source  or  receiver.  Once 
launched  it  travels  in  its  own  way.  If 
we  are  travelling  to  meet  it,  it  will  be 
arriving  at  us  more  quickly;  if  we  travel 
away  from  it,  it  will  reach  us  with  some 


56  Presidential  Address 

lag.  That  is  certain;  and  observation 
of  the  acceleration  or  retardation  is 
made  by  aid  of  Jupiter's  satellites.  We 
have  there  the  dial  of  a  clock,  to  or  from 
which  we  advance  or  recede  periodically. 
It  gains  while  we  approach  it,  it  loses 
while  we  recede  from  it,  it  keeps  right 
time  when  we  are  stationary  or  only 
moving  across  the  line  of  sight. 

But  then  of  course  it  does  not  matter 
whether  Jupiter  is  standing  still  and  we 
are  moving,  or  vice  versa:  it  is  a  case  of 
relative  motion  of  matter  again.  So  it 
is  if  we  observe  a  Doppler  effect  from  the 
right  and  left  hand  limbs  of  the  rotating 
sun.  True,  and  if  we  are  to  permit  no 
relative  motion  of  matter  we  must  use  a 
terrestrial  source,  clamped  to  the  earth 
as  our  receiver  is.  And  now  we  shall 
observe  nothing. 

But  not  because  there  is  nothing  to 
observe.  Lag  must  really  occur  if  we 
are  running  away  from  the  light,  even 
though  the  source  is  running  after  us  at 
the  same  pace:  unless  we  make  the 
assumption — true  only  for  corpuscular 


Continuity  57 

light — that  the  velocity  of  light  is  not 
an  absolute  thing,  but  is  dependent  on 
the  speed  of  the  source.  With  corpuscu- 
lar light  there  is  nothing  to  observe ;  with 
wave  light  there  is  something,  but  we 
cannot  observe  it. 

But  if  the  whole  solar  system  is  moving 
through  the  ether  I  see  no  reason  why 
the  relative  ether  drift  should  not 
be  observed  by  a  differential  residual 
effect  in  connection  with  Jupiter's  satel- 
lites or  the  right  and  left  limbs  of  the 
sun.  The  effect  must  be  too  small  to 
observe  without  extreme  precision,  but 
theoretically  it  ought  to  be  there.  In- 
asmuch however  as  relative  motion  of 
matter  with  respect  to  the  observer  is 
involved  in  these  effects,  it  may  be  held 
that  the  detection  of  a  uniform  drift  of 
the  solar  system  in  this  way  is  not  con- 
trary to  the  Principle  of  Relativity.  It 
is  contrary  to  some  statements  of  that 
Principle;  and  the  cogency  of  those 
statements  breaks  down,  I  think,  when- 
ever they  include  the  velocity  of  light; 
because  there  we  really  have  something 


58  Presidential  Address 

absolute  (in  the  only  sense  in  which  the 
term  can  have  a  physical  meaning)  with 
which  we  can  compare  our  own  motion, 
when  we  have  learnt  how. 

But  in  ordinary  astronomical  transla- 
tion—  translation  as  of  the  earth  in 
its  orbit — all  our  instruments,  all  our 
standards,  the  whole  contents  of  our 
laboratory,  are  moving  at  the  same  rate 
in  the  same  direction ;  under  those  condi- 
tions we  cannot  expect  to  observe  any- 
thing. Clerk  Maxwell  went  so  far  as 
to  say  that  if  every  particle  of  matter 
simultaneously  received  a  graduated 
blow  so  as  to  produce  a  given  constant 
acceleration  all  in  the  same  direction,  we 
should  be  unaware  of  the  fact.  He  did 
not  then  know  all  that  we  know  about 
radiation.  But  apart  from  that,  and 
limiting  ourselves  to  comparatively  slow 
changes  of  velocity,  our  standards  will 
inevitably  share  whatever  change  occurs. 
So  far  as  observation  goes,  everything 
will  be  practically  as  if  no  change  had 
occurred  at  all ; — though  that  may  not  be 
the  truth.  All  that  experiment  estab- 


Continuity  59 

lishes  is  that  there  have  so  far  always  been 
compensations;  so  that  the  attempt  to 
observe  motion  through  the  ether  is  being 
given  up  as  hopeless. 

Surely,  however,  the  minute  and  curi- 
ous compensations  cannot  be  accidental, 
they  must  be  necessary.  Yes,  they  are 
necessary ;  and  I  want  to  say  why.  Sup- 
pose the  case  were  one  of  measuring 
thermal  expansion;  and  suppose  every- 
thing had  the  same  temperature  and  the 
same  expansibility;  our  standards  would 
contract  or  expand  with  everything  else, 
and  we  could  observe  nothing ;  but  expan- 
sion would  occur  nevertheless.  That  is 
obvious,  but  the  following  assertion  is  not 
so  obvious.  If  everything  in  the  Uni- 
verse had  the  same  temperature,  no 
matter  what  that  temperature  was, 
nothing  would  be  visible  at  all ;  the  exter- 
nal world,  so  far  as  vision  went,  would  not 
appear  to  exist.  Visibility  depends  on 
radiation,  on  differential  radiation.  We 
must  have  differences  to  appeal  to  our 
senses,  they  are  not  constructed  for  uni- 
formity. 


60  Presidential  Address 

It  is  the  extreme  omnipresence  and 
uniformity  and  universal  agency  of  the 
ether  of  space  that  makes  it  so  difficult  to 
observe.  To  observe  anything  you  must 
have  differences.  If  all  actions  at  a  dis- 
tance are  conducted  at  the  same  rate 
through  the  ether,  the  travel  of  none  of 
them  can  be  observed.  Find  something 
not  conveyed  by  the  ether  and  there  is  a 
chance.  But  then  every  physical  action 
is  transmitted  by  the  ether,  and  in  every 
case  by  means  of  its  transverse  or  radi- 
ation-like activity. 

Except  perhaps  Gravitation.  That 
may  give  us  a  clue  some  day,  but  at 
present  we  have  not  been  able  to  detect 
its  speed  of  transmission  at  all.  No  plan 
has  been  devised  for  measuring  it.  No- 
thing short  of  the  creation  or  destruction 
of  matter  seems  likely  to  serve:  creation 
or  destruction  of  the  gravitational  unit, 
whether  it  be  an  atom  or  an  electron  or 
whatever  it  is.  Most  likely  the  unit  of 
weight  is  an  electron,  just  as  the  unit 
of  mass  is. 

The  so-called  non-Newtonian  Median- 


Continuity  61 

ics,  with  mass  and  shape  a  function  of 
velocity,  is  an  immediate  consequence  of 
the  electrical  theory  of  matter.  The  de- 
pendence of  inertia  and  shape  on  speed 
is  a  genuine  discovery  and,  I  believe, 
a  physical  fact.  The  Principle  of  Rela- 
tivity would  reduce  it  to  a  conventional 
fiction.  It  would  seek  to  replace  this  real 
change  in  matter  by  imaginary  changes  in 
time.  But  surely  we  must  admit  that 
Space  and  Time  are  essentially  unchange- 
able: they  are  not  at  the  disposal  even  of 
mathematicians;  though  it  is  true  that 
Pope  Gregory,  or  a  Daylight-saving  Bill, 
can  play  with  our  units,  can  turn  the  ^d 
of  October  in  any  one  year  into  the  I4th, 
or  can  make  the  sun  South  sometimes  at 
eleven  o'clock,  sometimes  at  twelve.1 

But  the  changes  of  dimension  and  mass 
due  to  velocity  are  not  conventions  but 

1  In  the  historical  case  of  governmental  interference  with 
the  calendar,  no  wonder  the  populace  rebelled.  Surely 
some  one  might  have  explained  to  the  authorities  that 
dropping  leap-year  for  the  greater  part  of  a  century  would 
do  all  that  was  wanted,  and  that  the  horrible  inconven- 
ience of  upsetting  all  engagements  and  shortening  a  single 
year  by  eleven  days  could  be  avoided. 


62  Presidential  Address 

realities;  so  I  urge,  on  the  basis  of  the 
electrical  theory  of  matter.  The  Fitz- 
gerald-Lorentz  hypothesis  I  have  an  af- 
fection for;  I  was  present  at  its  birth. 
Indeed  I  assisted  at  its  birth ;  for  it  was  in 
my  study  at  21  Waverley  Road,  Liver- 
pool, with  Fitzgerald  in  an  arm-chair,  and 
while  I  was  enlarging  on  the  difficulty 
of  reconciling  the  then  new  Michelson 
experiment  with  the  theory  of  astronomi- 
cal aberration  and  with  other  known 
facts,  that  he  made  his  brilliant  surmise: 
— "Perhaps  the  stone  slab  was  affected  by 
the  motion."  I  rejoined  that  it  was  a  45° 
shear  that  was  needed.  To  which  he 
replied,  "  Well  that's  all  right, — a  simple 
distortion. "  And  very  soon  he  said, 
"And  I  believe  it  occurs,  and  that  the 
Michelson  experiment  demonstrates  it." 
A  shortening  long-ways,  or  a  lengthening 
cross-ways  would  do  what  was  wanted. 
(See  Nature  for  16  June,  1892.) 

And  is  such  a  hypothesis  gratuitous? 
Not  at  all:  in  the  light  of  the  electrical 
theory  of  matter  such  an  effect  ought  to 
occur.  The  amount  required  by  the 


Continuity  63 

experiment,  and  given  by  the  theory,  is 
equivalent  to  a  shrinkage  of  the  earth's 
diameter  by  rather  less  than  three  inches, 
in  the  line  of  its  orbital  motion  through 
the  ether  of  space.  An  oblate  spheroid 
with  the  proper  eccentricity  has  all  the 
simple  geometrical  properties  of  a  station- 
ary sphere;  the  eccentricity  depends  in 
a  definite  way  on  speed,  and  becomes 
considerable  as  the  velocity  of  light  is 
approached. 

All  this  Professors  Lorentz  and  Lar- 
mor  very  soon  after,  and  quite  independ- 
ently, perceived;  though  this  is  only  one 
of  the  minor  achievements  in  the  electri- 
cal theory  of  matter  which  we  owe  to 
our  distinguished  visitor  Professor  H.  A. 
Lorentz. 

The  key  of  the  position,  to  my  mind, 
is  the  nature  of  cohesion.  I  regard  co- 
hesion as  residual  chemical  affinity,  a 
balance  of  electrical  attraction  over  re- 
pulsion between  groups  of  alternately 
charged  molecules.  Lateral  electrical 
attraction  is  diminished  by  motion;  so 
is  lateral  electric  repulsion.  In  cohesion 


64  Presidential  Address 

both  are  active,  and  they  nearly  balance 
At  anything  but  molecular  distance  they 
quite  balance,  but  at  molecular  dis- 
tance attraction  predominates.  It  is  the 
diminution  of  the  predominant  partner 
that  will  be  felt.  Hence  while  longi- 
tudinal cohesion,  or  cohesion  in  the  direc- 
tion of  motion,  remains  unchanged,  lateral 
cohesion  is  less ;  so  there  will  be  distortion, 
and  a  unit  cube  x  y  z  moving  along  x  with 
velocity  u  becomes  a  parallelepiped  with 
sides  i/k2,  k,  k;  where  i/k6  =  i  -  u2/v2. ' 
The  electrical  theory  of  matter  is  a 
positive  achievement,  and  has  positive 
results.  By  its  aid  we  make  experiments 
which  throw  light  upon  the  relation  be- 
tween matter  and  the  Ether  of  Space. 
The  Principle  of  Relativity,  which  seeks 
to  replace  it,  is  a  principle  of  negation,  a 

1  Different  modes  of  estimating  the  change  give  slightly 
different  results;  some  involve  a  compression  as  well  as  a 
distortion — in  fact  the  strain  associated  with  the  name  of 
Thomas  Young ;  the  details  are  rather  complicated  and  this 
is  not  the  place  to  discuss  them.  A  pure  distortion,  as 
specified  in  the  text,  is  simplest,  it  appears  to  be  in  accord 
with  all  the  experimental  facts — including  some  careful 
measurements  by  Bucherer, — and  I  rather  expect  it  to 
survive. 


Continuity  65 

negative  proposition,  a  statement  that 
observation  of  certain  facts  can  never  be 
made,  a  denial  of  any  relation  between 
matter  and  ether,  a  virtual  denial  that 
the  ether  exists.  Whereas  if  we  admit 
the  real  changes  that  go  on  by  reason  of 
rapid  motion,  a  whole  field  is  open  for 
discovery;  it  is  even  possible  to  investi- 
gate the  changes  in  shape  of  an  electron — 
appallingly  minute  though  it  is — as  it 
approaches  the  speed  of  light ;  and  prop- 
erties belonging  to  the  Ether  of  Space, 
evasive  though  it  be,  cannot  lag  far 
behind. 

Speaking  as  a  physicist  I  must  claim 
the  Ether  as  peculiarly  our  own  domain. 
The  study  of  molecules  we  share  with  the 
chemist,  and  matter  in  its  various  forms  is 
investigated  by  all  men  of  science,  but  a 
study  of  the  ether  of  space  belongs  to 
physics  only.  I  am  not  alone  in  feeling 
the  fascination  of  this  portentous  en- 
tity. Its  curiously  elusive  and  intangible 
character,  combined  with  its  universal 
and  unifying  permeance,  its  apparently 
infinite  extent,  its  definite  and  perfect 


66  Presidential  Address 

properties,  make  the  ether  the  most  inter- 
esting as  it  is  by  far  the  largest  and  most 
fundamental  ingredient  in  the  material 
cosmos. 

As  Sir  J.  J.  Thomson  said  at  Winnipeg: 

The  ether  is  not  a  fantastic  creation  of  the 
speculative  philosopher ;  it  is  as  essential  to  us 
as  the  air  we  breathe.  .  .  .  The  study  of  this 
all-pervading  substance  is  perhaps  the  most 
fascinating  and  important  duty  of  the  physicist. 

Matter  it  is  not,  but  material  it  is;  it 
belongs  to  the  material  universe  and  is 
to  be  investigated  by  ordinary  methods. 
But  to  say  this  is  by  no  means  to  deny 
that  it  may  have  mental  and  spiritual 
functions  to  subserve  in  some  other  order 
of  existence,  as  Matter  has  in  this. 

The  ether  of  space  is  at  least  the  great 
engine  of  continuity.  It  may  be  much 
more,  for  without  it  there  could  hardly 
be  a  material  universe  at  all.  Certainly, 
however,  it  is  essential  to  continuity; 
it  is  the  one  all-permeating  substance 
that  binds  the  whole  of  the  particles 
of  matter  together.  It  is  the  uniting 


Continuity  67 

and  binding  medium  without  which,  if 
matter  could  exist  at  all,  it  could  only 
exist  as  chaotic  and  isolated  fragments: 
and  it  is  the  universal  medium  of  com- 
munication between  worlds  and  between 
particles.  And  yet  it  is  possible  for 
people  to  deny  its  existence,  because  it  is 
unrelated  to  any  of  our  senses, — except 
sight,  and  to  that  only  in  an  indirect  and 
not  easily  recognised  fashion. 

To  illustrate  the  thorough  way  in 
which  we  may  be  unable  to  detect  what 
is  around  us  unless  it  has  some  link  or 
bond  which  enables  it  to  make  appeal, 
let  me  make  another  quotation  from  Sir 
J.  J.  Thomson's  Address  at  Winnipeg  in 
1909.  He  is  leading  up  to  the  fact  that 
even  single  atoms,  provided  they  are 
fully  electrified  with  the  proper  atomic 
charge,  can  be  detected  by  certain  deli- 
cate instruments — their  field  of  force 
bringing  them  within  our  ken — whereas  a 
whole  crowd  of  unelectrified  ones  would 
escape  observation. 

The  smallest  quantity  of  unelectrified  matter 
ever  detected  is  probably  that  of  neon,  one  of 


68  Presidential  Address 

the  inert  gases  of  the  atmosphere.  Professor 
Strutt  has  shown  that  the  amount  of  neon  in 
1/20  of  a  cubic  centimetre  of  the  air  at  ordinary 
pressures  can  be  detected  by  the  spectroscope; 
Sir  William  Ramsay  estimates  that  the  neon 
in  the  air  only  amounts  to  one  part  of  neon  in 
100,000  parts  of  air,  so  that  the  neon  in  1/20 
of  a  cubic  centimetre  of  air  would  only  occupy  at 
atmospheric  pressure  a  volume  of  half  a  mil- 
lionth of  a  cubic  centimetre.  When  stated  in 
this  form  the  quantity  seems  exceedingly  small, 
but  in  this  small  volume  there  are  about  ten 
million  million  molecules.  Now  the  population 
of  the  earth  is  estimated  at  about  fifteen  hun- 
dred millions,  so  that  the  smallest  number  of 
molecules  of  neon  we  can  identify  is  about  7000 
times  the  population  of  the  earth.  In  other 
frords,  if  we  had  no  better  test  for  the  existence 
of  a  man  than  we  have  for  that  of  an  unelectri- 
fied  molecule  we  should  come  to  the  conclusion 
that  the  earth  is  uninhabited. 

The  parable  is  a  striking  one,  for  on 
these  lines  it  might  legitimately  be  con- 
tended that  we  have  no  right  to  say  posi- 
tively that  even  space  is  uninhabited. 
All  we  can  safely  say  is  that  we  have  no 
means  of  detecting  the  existence  of  non- 
planetary  immaterial  dwellers,  and  that 


Continuity  69 

unless  they  have  some  link  or  bond  with 
the  material  they  must  always  be  physic- 
ally beyond  our  ken.  We  may  therefore 
for  practical  purposes  legitimately  treat 
them  as  non-existent  until  such  link 
is  discovered,  but  we  should  not  dog- 
matise about  them.  True  agnosticism 
is  legitimate,  but  not  the  dogmatic  and 
positive  and  gnostic  variety. 

For  I  hold  that  Science  is  incompetent 
to  make  comprehensive  denials,  even 
about  the  Ether,  and  that  it  goes  wrong 
when  it  makes  the  attempt.  Science 
should  not  deal  in  negations:  it  is  strong 
in  affirmations,  but  nothing  based  on 
abstraction  ought  to  presume  to  deny 
outside  its  own  region.  It  often  happens 
that  things  abstracted  from  and  ignored 
by  one  branch  of  science  may  be  taken 
into  consideration  by  another: 

Thus,  Chemists  ignore  the  Ether. 

Mathematicians  may  ignore  experi- 
mental difficulties. 

Physicists  ignore  and  exclude  live 
things. 


70  Presidential  Address 

Biologists  exclude  Mind  and  Design. 

Psychologists  may  ignore  human  origin 
and  human  destiny. 

Folk-lore  students  and  comparative 
Mythologists  need  not  trouble  about 
what  modicum  of  truth  there  may  be 
in  the  legends  which  they*  are  collecting 
and  systematising. 

And  Microscopists  may  ignore  the 
stars. 

Yet  none  of  these  ignored  things  should 
be  denied. 

Denial  is  no  more  infallible  than  asser- 
tion. There  are  cheap  and  easy  kinds 
of  scepticism,  just  as  there  are  cheap 
and  easy  kinds  of  dogmatism;  in  fact 
scepticism  can  become  viciously  dog- 
matic, and  science  has  to  be  as  much  on 
its  guard  against  personal  predilection  in 
the  negative  as  in  the  positive  direction. 
An  attitude  of  universal  denial  may  be 
very  superficial. 

To  doubt  everything  or  to  believe  everything 
are  two  equally  convenient  solutions;  both  dis- 
pense with  the'  necessity  of  reflection. 


Continuity  71 

All  intellectual  processes  are  based  on 
abstraction, — that  is  on  concentrated 
attention  directed  to  a  selected  portion, 
with  limitation  of  scope,  and  elimination 
of  whatever  may  be  regarded  as  unessen- 
tial or  irrelevant.  For  instance,  History 
must  ignore  a  great  multitude  of  facts 
in  order  to  treat  any  intelligently:  it 
selects.  So  does  Art;  and  that  is  why  a 
drawing  is  clearer  than  reality.  Science 
makes  a  diagram  of  reality,  displaying  the 
works,  like  a  skeleton  clock.  Anatomists 
dissect  out  the  nervous  system,  the  blood- 
vessels, and  the  muscles,  and  depict  them 
separately, — there  must  be  discrimin- 
ation for  intellectual  grasp, — but  in  life 
they  are  all  merged  and  co-operating 
together;  they  do  not  really  work  separ- 
ately, though  they  may  be  studied  separ- 
ately. A  scalpel  discriminates:  a  dagger 
or  a  bullet  crashes  through  everything. 
That  is  life, — or  rather  death.  The  laws 
of  nature  are  a  diagrammatic  frame- 
work, analysed  or  abstracted  out  of  the 
full  comprehensiveness  of  reality. 

Hence  it  is  that  Science  has  no  au- 


72  Presidential  Address 

thority  in  denials.  To  deny  effectively 
needs  much  more  comprehensive  know- 
ledge than  to  assert.  And  abstraction  is 
essentially  not  comprehensive:  one  can- 
not have  it  both  ways.  Science  employs 
the  methods  of  abstraction  and  thereby 
makes  its  discoveries. 

The  reason  why  some  physiologists 
insist  so  strenuously  on  the  validity  and 
self-sufficiency  of  the  laws  of  physics  and 
chemistry,  and  resist  the  temptation  to 
appeal  to  unknown  causes — even  though 
the  guiding  influence  and  spontaneity  of 
living  things  are  occasionally  conspicuous 
as  well  as  inexplicable — is  that  they  are 
keen  to  do  their  proper  work;  and  their 
proper  work  is  to  pursue  the  laws  of 
ordinary  physical  Energy  into  the  intri- 
cacies of  "colloidal  electrolytic  structures 
of  great  chemical  complexity"  and  to 
study  its  behaviour  there. 

What  we  have  clearly  to  grasp,  on  their 
testimony,  is  that  for  all  the  terrestrial 
manifestations  of  life. the  ordinary  phys- 
ical and  chemical  processes  have  to  serve. 
There  are  not  new  laws  for  living  matter, 


Continuity  73 

and  old  laws  for  non-living,  the  laws  are 
the  same;  or  if  ever  they  differ,  the 
burden  of  proof  rests  on  him  who  sustains 
the  difference.  The  conservation  of  en- 
ergy, the  laws  of  chemical  combination, 
the  laws  of  electric  currents,  of  radiation, 
etc.,  etc., — all  the  laws  of  Chemistry  and 
Physics, — may  be  applied  without  hesita- 
tion in  the  Organic  domain.  Whether 
they  are  sufficient  is  open  to  question, 
but  as  far  as  they  go  they  are  necessary; 
and  it  is  the  business  of  the  physiologist 
to  seek  out  and  demonstrate  the  action 
of  those  laws  in  every  vital  action. 

This  is  clearly  recognised  by  the  leaders, 
and  in  the  definition  of  Physiology  by 
Burdon  Sanderson  he  definitely  limited 
it  to  the  study  of  "ascertainable  char- 
acters of  a  chemical  and  physical  type." 
In  his  Address  to  the  Sub-section  of 
Anatomy  and  Physiology  at  York  in 
1 88 1  he  spoke  as  follows: 

It  would  give  you  a  true  idea  of  the  nature 
of  the  great  advance  which  took  place  about  the 
middle  of  this  century  if  I  were  to  define  it  as 
the  epoch  of  the  death  of  ' 'vitalism."  Before 


74  Presidential  Address 

that  time,  even  the  greatest  biologists — e.g., 
J.  M tiller — recognised  that  the  knowledge  bio- 
logists possessed  both  of  vital  and  physical 
phenomena  was  insufficient  to  refer  both  to  a 
common  measure.  The  method,  therefore,  was 
to  study  the  processes  of  life  in  relation  to  each 
other  only.  Since  that  time  it  has  become 
fundamental  in  our  science  not  to  regard  any 
vital  process  as  understood  at  all  unless  it  can 
be  brought  into  relation  with  physical  standards, 
and  the  methods  of  physiology  have  been  based 
exclusively  on  this  principle.  The  most  efficient 
cause  [conducing  to  the  change]  was  the  progress 
which  had  been  made  in  physics  and  chemistry, 
and  particularly  those  investigations  which  led 
to  the  establishment  of  the  doctrine  of  the  Con- 
servation of  Energy.  ...-  .  . 

Investigators  who  are  now  working  with  such 
earnestness  in  all  parts  of  the  world  for  the  ad- 
vance of  physiology,  have  before  them  a  definite 
and  well-understood  purpose,  that  purpose  being 
to  acquire  an  exact  knowledge  of  the  chemical 
and  physical  processes  of  animal  life  and  of  the 
self-acting  machinery  by  which  they  are  regu- 
lated for  the  general  good  of  the  organism.  The 
more  singly  and  straightforwardly  we  direct  our 
efforts  to  these  ends,  the  sooner  we  shall  attain 
to  the  still  higher  purpose — the  effectual  applica- 
tion of  our  knowledge  for  the  increase  of  human 
happiness. 


Continuity  75 

Professor  Gotch,  whose  recent  loss  we 
have  to  deplore,  puts  it  even  more 
strongly: 

It  is  essentially  unscientific  [he  says]  to  say 
that  any  physiological  phenomenon  is  caused 
by  vital  force. 

I  observe  that  by  some  critics  I  have 
been  called  a  vitalist,  and  in  a  sense  I  am ; 
but  I  am  not  a  vitalist  if  vitalism  means 
an  appeal  to  an  undefined  ''vital  force" 
(an  objectionable  term  I  have  never 
thought  of  using)  as  against  the  laws 
of  Chemistry  and  Physics.  Those  laws 
must  be  supplemented,  but  need  by  no 
means  be  superseded.  The  business  of 
science  is  to  trace  out  their  mode  of 
action  everywhere,  as  far  and  as  fully  as 
possible;  and  it  is  a  true  instinct  which 
resents  the  mediaeval  practice  of  freely 
introducing  spiritual  and  unknown  causes 
into  working  science.  In  science  an 
appeal  to  occult  qualities  must  be  illegiti- 
mate, and  be  a  barrier  to  experiment  and 
research  generally;  as,  when  anything  is 
called  an  Act  of  God — and  when  no  more  is 


76  Presidential  Address 

said.  The  occurrence  is  left  unexplained. 
As  an  ultimate  statement  such  a  phrase 
may  be  not  only  true  but  universal  in 
its  application.  But  there  are  always 
proximate  explanations  which  may  be 
looked  for  and  discovered  with  patience. 
So,  lightning,  earthquakes,  and  other 
portents  are  reduced  to  natural  causes. 
No  ultimate  explanation  is  ever  attained 
by  science:  proximate  explanations  only. 
They  are  what  it  exists  for;  and  it  is  the 
business  of  scientific  men  to  seek  them. 

To  attribute  the  rise  of  sap  to  vital 
force  would  be  absurd,  it  would  be  giving 
up  the  problem  and  stating  nothing  at  all. 
The  way  in  which  osmosis  acts  to  produce 
the  remarkable  and  surprising  effect  is 
discoverable  and  has  been  discovered. 

So  it  is  always  in  science,  and  its  pro- 
gress began  when  unknown  causes  were 
eliminated  and  treated  as  non-existent. 
Those  causes,  so  far  as  they  exist,  must 
establish  their  footing  by  direct  investiga- 
tion and  research;  carried  on  in  the  first 
instance  apart  from  the  long  recognised 
branches  of  science,  until  the  time  when 


Continuity  77 

they  too  have  become  sufficiently  definite 
to  be  entitled  to  be  called  scientific. 
Outlandish  Territories  may  in  time  be  in- 
corporated as  States,  but  they  must  make 
their  claim  good  and  become  civilised 
first. 

It  is  well  for  people  to  understand  this 
definite  limitation  of  scope  quite  clearly, 
else  they  wrest  the  splendid  work  of 
biologists  to  their  own  confusion, — helped 
it  is  true  by  a  few  of  the  more  robust  or 
less  responsible  theorisers,  among  whom 
are  some  who  should  be  better  informed 
and  more  carefully  critical  in  their  philo- 
sophising utterances. 

But,  as  is  well  known,  there  are  more 
than  a  few  biologists  who,  when  taking 
a  broad  survey  of  their  subject,  clearly 
perceive  and  teach  that  before  all  the 
actions  of  live  things  are  fully  explained, 
some  hitherto  excluded  causes  must  be 
postulated.  Ever  since  the  time  of  J.  R. 
Mayer  it  has  been  becoming  more  and 
more  certain  that  as  regards  performance 
of  work,  a  living  thing  obeys  the  laws  of 
physics,  like  everything  else; 'but  un- 


78  Presidential  Address 

doubtedly  it  initiates  processes  and  pro- 
duces results  that  without  it  could  not 
have  occurred, — from  a  bird's  nest  to  a 
honeycomb,  from  a  deal  box  to  a  warship. 
The  behaviour  of  a  ship  firing  shot  and 
shell  is  explicable  in  terms  of  energy,  but 
the  discrimination  which  it  exercises  be- 
tween friend  and  foe  is  not  so  explicable. 
There  is  plenty  of  physics  and  chemistry 
and  mechanics  about  every  vital  action, 
but  for  a  complete  understanding  of  it 
something  beyond  physics  and  chemistry 
is  needed. 

And  life  introduces  an  incalculable 
element.  The  vagaries  of  a  fire  or  a 
cyclone  could  all  be  predicted  by  La- 
place's Calculator,  given  the  initial 
positions,  velocities,  and  the  law  of  accel- 
eration of  the  molecules;  but  no  mathe- 
matician could  calculate  the  orbit  of  a 
common  house-fly.  A  physicist  into  whose 
galvanometer  a  spider  had  crept  would  be 
liable  to  get  phenomena  of  a  kind  quite 
inexplicable,  until  he  discovered  the  super- 
natural, i.e.,  literally  superphysical,  cause. 
I  will  risk  the  assertion  that  Life  intro- 


Continuity  79 

duces  something  incalculable  and  purpose- 
ful amid  the  laws  of  physics;  it  thus 
distinctly  supplements  those  laws,  though 
it  leaves  them  otherwise  precisely  as  they 
were  and  obeys  them  all. 

We  see  only  its  effect,  we  do  not  see 
Life  itself.  Conversion  of  Inorganic  into 
Organic  is  effected  always  by  living 
organisms.  The  conversion  under  those 
conditions  certainly  occurs,  and  the  pro- 
cess may  be  studied.  Life  appears  nec- 
essary to  the  conversion;  which  clearly 
takes  place  under  the  guidance  of  life, 
though  in  itself  it  is  a  physical  and 
chemical  process.  Many  laboratory  con- 
versions take  place  under  the  guidance  of 
life,  and,  but  for  the  experimenter,  would 
not  have  occurred. 

Again,  putrefaction,  and  fermentation, 
and  purification  of  rivers,  and  disease, 
are  not  purely  and  solely  chemical  pro- 
cesses. Chemical  processes  they  are,  but 
they  are  initiated  and  conducted  by 
living  organisms.  Just  when  medicine  is 
becoming  biological,  and  when  the  hope 
of  making  the  tropical  belt  of  the  earth 


8o  Presidential  Address 

healthily  habitable  by  energetic  races 
is  attracting  the  attention  of  people  of 
power,  philosophising  biologists  should 
not  attempt  to  give  their  science  away 
to  Chemistry  and  Physics.  Sections  D 
and  H  and  I  and  K  are  not  really  sub- 
servient to  A  and  B.  Biology  is  an 
independent  science,  and  it  is  served,  not 
dominated,  by  Chemistry  and  Physics. 

Scientific  men  are  hostile  to  supersti- 
tion, and  rightly  so,  for  a  great  many 
popular  superstitions  are  both  annoying 
and  contemptible;  yet  occasionally  the 
term  may  be  wrongly  applied  to  practices 
of  which  the  theory  is  unknown.  To  a 
superficial  observer  some  of  the  practices 
of  biologists  themselves  must  appear 
grossly  superstitious.  To  combat  malaria 
Sir  Ronald  Ross  does  not  indeed  erect  an 
altar ;  no,  he  oils  a  pond, — making  libation 
to  its  presiding  genii.  What  can  be  more 
ludicrous  than  the  curious  and  evidently 
savage  ritual,  insisted  on  by  United  States 
Officers,  at  that  hygienically  splendid 
achievement  the  Panama  Canal, — the 
ritual  of  punching  a  hole  in  every  dis- 


Continuity  81 

carded  tin,  with  the  object  of  keeping 
off  disease!  What  more  absurd,  again — 
in  superficial  appearance — than  the  prac- 
tice of  burning  or  poisoning  a  soil  to  make 
it  extra  fertile ! 

Biologists  in  their  proper  field  are 
splendid,  and  their  work  arouses  keen 
interest  and  enthusiasm  in  all  whom  they 
guide  into  their  domain.  Some  of  them 
do  their  work  by  intense  concentration, 
by  narrowing  down  their  scope,  not  by 
taking  a  wide  survey  or  a  comprehensive 
grasp.  Suggestions  of  broader  views  and 
outlying  fields  of  knowledge  seem  foreign 
to  the  intense  worker,  and  he  resents  them^ 
For  his  own  purpose  he  wishes  to  ignore 
them,  and  practically  he  may  be  quite 
right.  The  folly  of  negation  is  not  his, 
but  belongs  to  those  who  misinterpret  or 
misapply  his  utterances,  and  take  him  as 
a  guide  in  a  region  where,  for  the  time  at 
least,  he  is  a  stranger.  Not  by  such  aid 
is  the  universe  in  its  broader  aspects  to  be 
apprehended.  If  people  in  general  were 
better  acquainted  with  science  they  would 
not  make  these  mistakes.  They  would 


82  Presidential  Address 

realise  both  the  learning  and  the  limita- 
tions, make  use  of  the  one  and  allow  for 
the  other,  and  not  take  the  recipe  of  a 
practical  worker  for  a  formula  wherewith 
to  interpret  the  Universe. 

What  appears  to  be  quite  certain  is  that 
there  can  be  no  terrestrial  manifestation 
of  life  without  matter.  Hence  naturally 
they  say,  or  they  approve  such  sayings  as, 
"I  discern  in  matter  the  promise  and 
potency  of  all  forms  of  life."  Of  all 
terrestrial  manifestations  of  life,  certainly; 
how  else  could  it  manifest  itself  save 
through  matter?  "I  detect  nothing  in 
the  organism  but  the  laws  of  Chemistry 
and  Physics,"  it  is  said.  Very  well: 
naturally  enough.  That  is  what  they 
are  after;  they  are  studying  the  physical 
and  chemical  aspects  or  manifestations 
of  life.  But  life  itself — life  and  mind  and 
consciousness — they  are  not  studying, 
and  they  exclude  them  from  their  pur- 
view. Matter  is  what  appeals  to  our 
senses  here  and  now;  Materialism  is  ap- 
propriate to  the  material  world;  not  as  a 
philosophy  but  as  a  working  creed,  as  a 


Continuity  83 

proximate  and  immediate  formula  for 
guiding  research.  Everything  beyond 
that  belongs  to  another  region,  and  must 
be  reached  by  other  methods.  To  explain 
the  Psychical  in  terms  of  Physics  and 
Chemistry  is  simply  impossible;  hence 
there  is  a  tendency  to  deny  its  existence, 
save  as  an  epiphenomenon.  But  all  such 
philosophising  is  unjustified,  and  is  really 
bad  Metaphysics. 

So  if  ever  in  their  enthusiasm  scientific 
workers  go  too  far  and  say  that  the  things 
they  exclude  from  study  have  no  existence 
in  the  universe,  we  must  appeal  against 
them  to  direct  experience.  We  ourselves 
are  alive,  we  possess  life  and  mind  and 
consciousness,  we  have  first-hand  experi- 
ence of  these  things  quite  apart  from 
laboratory  experiments.  They  belong  to 
the  common  knowledge  of  the  race. 
Births,  deaths,  and  marriages  are  not 
affairs  of  the  biologist,  but  of  humanity; 
they  went  on  before  a  single  one  of  them 
was  understood,  before  a  vestige  of 
science  existed.  We  ourselves  are  the 
laboratory  in  which  men  of  science, 


84  Presidential  Address 

psychologists  and  others,  make  experi- 
ments. They  can  formulate  our  processes 
of  digestion,  and  the  material  concomi- 
tants of  willing,  of  sensation,  of  thinking; 
but  the  hidden  guiding  entities  they  do 
not  touch. 

So  also  if  any  philosopher  tells  you  that 
you  do  not  exist,  or  that  the  external 
world  does  not  exist,  or  that  you  are  an 
automaton  without  free  will,  that  all 
your  actions  are  determined  by  outside 
causes  and  that  you  are  not  responsible, — 
or  that  a  body  cannot  move  out  of  its 
place,  or  that  Achilles  cannot  catch  a 
tortoise, — then  in  all  those  cases  appeal 
must  be  made  to  twelve  average  men, 
unsophisticated  by  special  studies.  There 
is  always  a  danger  of  error  in  interpreting 
experience,  or  in  drawing  inferences  from 
it;  but  in  a  matter  of  bare  fact,  based  on 
our  own  first-hand  experience,  we  are 
able  to  give  a  verdict.  We  may  be  mis- 
taken as  to  the  nature  of  what  we  see; 
stars  may  look  to  us  like  bright  specks  in 
a  dome;  but  the  fact  that  we  see  them 
admits  of  no  doubt.  So  also  Conscious- 


Continuity  85 

ness  and  Will  are  realities  of  which  we  are 
directly  aware,  just  as  directly  as  we  are 
of  motion  and  force,  just  as  clearly  as  we 
apprehend  the  philosophising  utterances 
of  an  Agnostic.  The  process  of  seeing, 
the  plain  man  does  not  understand;  he 
does  not  recognise  that  it  is  a  method  of 
etherial  telegraphy;  he  knows  nothing  of 
the  ether  and  its  ripples,  nor  of  the  retina 
and  its  rods  and  cones,  nor  of  nerve  and 
brain  processes;  but  he  sees  and  he  hears 
and  he  touches,  and  he  wills  and  he  thinks 
and  is  conscious.  This  is  not  an  appeal 
to  the  mob  as  against  the  philosopher; 
it  is  appeal  to  the  experience  of  untold 
ages  as  against  the  studies  of  a  generation. 
How  consciousness  became  associated 
with  matter,  how  life  exerts  guidance 
over  chemical  and  physical  forces,  how 
mechanical  motions  are  translated  into 
sensations, — all  these  things  are  puzzling, 
and  demand  long  study.  But  the  fact 
that  these  things  are  so  admits  of  no  doubt ; 
and  difficulty  of  explanation  is  no  argu- 
ment against  them.  The  blind  man 
restored  to  sight  had  no  opinion  as  to 


86  Presidential  Address 

how  he  was  healed,  nor  could  he  vouch 
for  the  moral  character  of  the  Healer, 
but  he  plainly  knew  that  whereas  he  was 
blind  now  he  saw.  About  that  fact  he 
was  the  best  possible  judge.  So  it  is  also 
with  "this  main  miracle  that  thou  art 
thou,  With  power  on  thine  own  act  and 
on  the  world." 

But  although  Life  and  Mind  may  be 
excluded  from  Physiology,  they  are  not 
excluded  from  Science.  Of  course  not. 
It  is  not  reasonable  to  say  that  things 
necessarily  elude  investigation  merely 
because  we  do  not  knock  against  them. 
Yet  the  mistake  is  sometimes  made. 
The  ether  makes  no  appeal  to  sense, 
therefore  some  are  beginning  to  say  that 
it  does  not  exist.  Mind  is  occasionally 
put  into  the  same  predicament.  Life  is 
not  detected  in  the  laboratory,  save  in  its 
physical  and  chemical  manifestations; 
but  we  may  have  to  admit  that  it  guides 
processes  nevertheless.  It  may  be  called 
a  catalytic  agent. 

To  understand  the  action  of  life  itself, 
the  simplest  plan  is  not  to  think  of  a 


Continuity  87 

microscopic  organism,  or  any  unfamiliar 
animal,  but  to  make  use  of  our  own 
experience  as  living  beings.  Any  positive 
instance  serves  to  stem  a  comprehensive 
denial;  and  if  the  reality  of  mind  and 
guidance  and  plan  is  denied  because  they 
make  no  appeal  to  sense,  then  think  how 
the  world  would  appear  to  an  observer  to 
whom  the  existence  of  men  was  unknown 
and  undiscoverable,  while  yet  all  laws 
and  activities  of  nature  went  on  as  they 
do  now. 

Suppose,  then,  that  man  made  no 
appeal  to  the  senses  of  an  observer  of  this 
planet.  Suppose  an  outside  observer 
could  see  all  the  events  occurring  in  the 
world,  save  only  that  he  could  not  see 
animals  or  men.  He  would  describe 
what  he  saw  much  as  we  have  to  describe 
the  activities  initiated  by  life. 

If  he  looked  at  the  Firth  of  Forth,  for 
instance,  he  would  see  piers  arising  in 
the  water,  beginning  to  sprout,  reaching 
across  in  strange  manner  till  they  actually 
join  or  are  joined  by  pieces  attracted 
up  from  below  to  complete  the  circuit  (a 


88  Presidential  Address 

solid  circuit  round  the  current) .  He  would 
see  a  sort  of  bridge  or  filament  thus  con- 
structed, from  one  shore  to  the  other,  and 
across  this  bridge  insect-like  things  crawl- 
ing and  returning  for  no  very  obvious 
reason. 

Or  let  him  look  at  the  Nile,  and  recog- 
nise the  meritorious  character  of  that 
river  in  promoting  the  growth  of  vegeta- 
tion in  the  desert.  Then  let  him  see  a 
kind  of  untoward  crystallisation  growing 
across  and  beginning  to  dam  the  benefi- 
cent stream.  Blocks  fly  to  their  places 
by  some  kind  of  polar  forces;  "we  cannot 
doubt"  that  it  is  by  helio-  or  other  tropism. 
There  is  no  need  to  go  outside  the  laws  of 
mechanics  and  physics,  there  is  no  diffi- 
culty about  supply  of  energy — none  what- 
ever,— materials  in  tin  cans  are  consumed 
which  amply  account  for  all  the  energy; 
and  all  the  laws  of  physics  are  obeyed. 
The  absence  of  any  design,  too,  is  mani- 
fest; for  the  effect  of  the  structure  is  to 
flood  an  area  upsteam  which  might  have 
been  useful,  and  to  submerge  a  structure 
of  some  beauty;  while  down  stream  its 


Continuity  89 

effect  is  likely  to  be  worse,  for  it  would 
block  the  course  of  the  river  and  waste  it 
on  the  desert,  were  it  not  that  fortunately 
some  leaks  develop  and  a  sufficient  supply 
still  goes  down — goes  down  in  fact  more 
equably  than  before :  so  that  the  ultimate 
result  is  beneficial  to  vegetation,  and 
simulates  intention. 

If  told  concerning  either  of  these  struc- 
tures that  an  engineer,  a  designer  in 
London,  called  Benjamin  Baker,  had 
anything  to  do  with  it,  the  idea  would  be 
preposterous.  One  conclusive  argument 
is  final  against  such  a  superstitious  hypo- 
thesis— he  is  not  there,  and  a  thing 
plainly  cannot  act  where  it  is  not.  But 
although  we,  with  our  greater  advantages, 
perceive  that  the  right  solution  for  such 
an  observer  would  be  the  recognition  of 
some  unknown  agency  or  agent,  it  must 
be  admitted  that  an  explanation  in  terms 
of  a  vague  entity  called  vital  force  would 
be  useless,  and  might  be  so  worded  as  to 
be  misleading;  whereas  a  statement  in 
terms  of  mechanics  and  physics  could  be 
clear  and  definite  and  true  as  far  as  it 


90  Presidential  Address 

went,  though  it  must  necessarily  be 
incomplete. 

And  note  that  what  we  observe,  in 
such  understood  cases,  is  an  Interaction 
of  Mind  and  Matter;  not  Parallelism  nor 
Epiphenomenalism  nor  anything  strained 
or  difficult,  but  a  straightforward  utilisa- 
tion of  the  properties  of  matter  and  energy 
for  purposes  conceived  in  the  mind,  and 
executed  by  muscles  guided  by  acts  of  will. 

But,  it  will  be  said,  this  is  unfair,  for 
we  know  that  there  is  design  in  the  Forth 
Bridge  or  the  Nile  Dam,  we  have  seen  the 
plans  and  understand  the  agencies  at 
work :  we  know  that  it  was  conceived  and 
guided  by  life  and  mind,  it  is  unfair  to 
quote  this  as  though  it  could  simulate  an 
automatic  process. 

Not  at  all,  say  the  extreme  school  of 
biologists  whom  I  am  criticising,  or  ought 
to  say  if  they  were  consistent,  there  is 
nothing  but  Chemistry  and  Physics  at 
work  anywhere;  and  the  mental  activ- 
ity apparently  demonstrated  by  those 
structures  is  only  an  illusion,  an  epi- 
phenomenon;  the  laws  of  chemistry 


Continuity  91 

and  physics  are  supreme,  and  they  are 
sufficient  to  account  for  everything! 

Well,  they  account  for  things  up  to  a 
point ;  they  account  in  part  for  the  colour 
of  a  sunset,  for  the  majesty  of  a  mountain 
peak,  for  the  glory  of  animate  existence. 
But  do  they  account  for  everything  com- 
pletely? Do  they  account  for  our  own 
feeling  of  joy  and  exaltation,  for  our  sense 
of  beauty,  for  the  manifest  beauty  existing 
throughout  nature?  Do  not  these  things 
suggest  something  higher  and  nobler  and 
more  joyous,  something  for  the  sake  of 
which  all  the  struggle  for  existence  goes 
on? 

Surely  there  must  be  a  deeper  meaning 
involved  in  natural  objects.  Orthodox 
explanations  are  only  partial,  though 
true  as  far  as  they  go.  When  we  examine 
each  particoloured  pinnule  in  a  peacock's 
tail,  or  hair  in  a  zebra's  hide,  and  realise 
that  the  varying  shades  on  each  are  so 
placed  as  to  contribute  to  the  general  de- 
sign and  pattern,  it  becomes  exceedingly 
difficult  to  explain  how  this  organised 
co-operation  of  parts,  this  harmonious 


92  Presidential  Address 

distribution  of  pigment  cells,  has  come 
about  on  merely  mechanical  principles. 
It  would  be  as  easy  to  explain  the  sprout- 
ing of  the  cantilevers  of  the  Forth  Bridge 
from  its  piers,  or  the  flocking  of  the  stones 
of  the  Nile  Dam  by  chemiotaxis.  Flowers 
attract  insects  for  fertilisation;  and  fruit 
tempts  birds  to  eat  it  in  order  to  carry 
seeds.  But  these  explanations  cannot 
be  final.  We  have  still  to  explain  the 
insects.  So  much  beauty  cannot  be 
necessary  merely  to  attract  their  atten- 
tion. We  have  further  to  explain  this 
competitive  striving  towards  life.  Why 
do  things  struggle  to  exist?  Surely  the 
effort  must  have  some  significance,  the 
development  some  aim.  We  thus  reach 
the  problem  of  Existence  itself,  and  the 
meaning  of  Evolution. 

The  mechanism  whereby  existence  en- 
trenches itself  is  manifest,  or  at  least  has 
been  to  a  large  extent  discovered.  Natur- 
al Selection  is  a  vera  causa,  so  far  as  it  goes; 
but  if  so  much  beauty  is  necessary  for  in- 
sects, what  about  the  beauty  of  a  land- 
scape or  of  clouds?  What  utilitarian 


Continuity  93 

object  does  that  subserve  ?  Beauty  in  gen- 
eral is  not  taken  into  account  by  science. 
Very  well,  that  may  be  all  right,  but  it 
exists  nevertheless.  It  is  not  my  function 
to  discuss  it.  No ;  but  it  is  my  function 
to  remind  you  and  myself  that  our  studies 
do  not  exhaust  the  Universe,  and  that  if 
we  dogmatise  in  a  negative  direction,  and 
say  that  we  can  reduce  everything  to 
physics  and  chemistry,  we  gibbet  our- 
selves as  ludicrously  narrow  pedants, 
and  are  falling  far  short  of  the  richness 
and  fulness  of  our  human  birthright. 
How  far  preferable  is  the  reverent  atti- 
tude of  the  Eastern  Poet — 

The  world  with  eyes  bent  upon  thy  feet  stands 
in  awe  with  all  its  silent  stars. 

Superficially  and  physically  we  are 
very  limited.  Our  sense  organs  are 
adapted  to  the  observation  of  matter; 
and  nothing  else  directly  appeals  to  us. 
Our  nerve-muscle-system  is  adapted  to 
the  production  of  motion  in  matter,  in 
desired  ways;  and  nothing  else  in  the 
material  world  can  we  accomplish.  Our 


94  Presidential  Address 

brain  and  nerve  systems  connect  us  with 
the  rest  of  the  physical  world.  Our 
senses  give  us  information  about  the 
movements  and  arrangements  of  matter. 
Our  muscles  enable  us  to  produce  changes 
in  those  distributions.  That  is  our  equip- 
ment for  human  life;  and  human  history 
is  a  record  of  what  we  have  done  with 
these  parsimonious  privileges. 

Our  brain,  which  by  some  means  yet 
to  be  discovered  connects  us  with  the 
rest  of  the  material  world,  has  been 
thought  partially  to  disconnect  us  from 
the  mental  and  spiritual  realm,  to  which 
we  really  belong  but  from  which  for  a 
time  and  for  practical  purposes  we  are 
isolated.  Our  common  or  social  associ- 
ation with  matter  gives  us  certain  oppor- 
tunities and  facilities,  combined  with 
obstacles  and  difficulties  which  are  them- 
selves opportunities  for  struggle  and 
effort. 

Through  matter  we  become  aware  of 
each  other,  and  can  communicate  with 
those  of  our  fellows  who  have  ideas  suffi- 
ciently like  our  own  for  them,  to  be  stimu- 


Continuity  95 

lated  into  activity  by  a  merely  physical 
process  set  in  action  by  ourselves.  By  a 
timed  succession  of  vibratory  movements 
(as  in  speech  and  music),  or  by  a  static 
distribution  of  materials  (as  in  writing, 
painting,  and  sculpture),  we  can  carry  on 
intelligent  intercourse  with  our  fellows; 
and  we  get  so  used  to  these  ingenious 
and  roundabout  methods,  that  we  are 
apt  to  think  of  them  and  their  like  as  not 
only  the  natural  but  as  the  only  possible 
modes  of  communication,  and  to  imagine 
that  anything  more  direct  would  disar- 
range the  whole  fabric  of  science. 

It  is  clearly  true  that  our  bodies  con- 
stitute the  normal  means  of  manifesting 
ourselves  to  each  other  while  on  the 
planet;  and  that  if  the  physiological 
mechanism  whereby  we  accomplish  ma- 
terial acts  is  injured,  the  conveyance 
of  our  meaning  and  the  display  of  our 
personality  inevitably  and  correspond- 
ingly suffer. 

So  conspicuously  is  this  the  case  that 
it  has  been  possible  to  suppose  that  the 
communicating  mechanism,  formed  and 


96  Presidential  Address 

worked  by  us,  is  the  whole  of  our  exist- 
ence; and  that  we  are  essentially  nothing 
but  the  machinery  by  which  we  are 
known.  We  find  the  machinery  utilising 
nothing  but  well-known  forms  of  energy, 
and  subject  to  all  the  laws  of  chemistry 
and  physics, — it  would  be  strange  if  it 
were  not  so, — and  from  that  fact  we  try  to 
draw  valid  deductions  as  to  our  nature, 
and  as  to  the  impossibility  of  our  exist- 
ing apart  from  and  independent  of  these 
temporary  modes  of  material  activity  and 
manifestation.  We  so  uniformly  employ 
them,  in  our  present  circumstances,  that 
we  should  be  on  our  guard  against  de- 
ception due  to  this  very  uniformity.  Ma- 
terial bodies  are  all  that  we  have  any 
control  over,  are  all  that  we  are  experi- 
mentally aware  of;  anything  that  we 
can  do  with  these  is  open  to  us;  any  con- 
clusions we  can  draw  about  them  may  be 
legitimate  and  true.  But  to  step  outside 
their  province  and  to  deny  the  existence 
of  any  other  region  because  we  have  no 
sense  organ  for  its  appreciation,  or  be- 
cause (like  the  Ether)  it  is  too  uniformly 


Continuity  97 

omnipresent  for  our  ken,  is  to  wrest 
our  advantages  and  privileges  from  their 
proper  use  and  apply  them  to  our  own 
misdirection. 

But  if  we  have  learnt  from  science  that 
Evolution  is  real,  we  have  learnt  a  great 
deal.  I  must  not  venture  to  philoso- 
phise, but  certainly  from  the  point  of 
view  of  science  Evolution  is  a  great 
reality.  Surely  evolution  is  not  an  illu- 
sion; surely  the  universe  progresses  in 
time.  Time  and  Space  and  Matter  are 
abstractions,  but  are -none  the  less  real: 
they  are  data  given  by  experience;  and 
Time  is  the  keystone  of  evolution.  ' '  Thy 
centuries  follow  each  other,  perfecting  a 
small  wild  flower. " 

We  abstract  from  living  moving 
Reality  a  certain  static  aspect,  and  we 
call  it  Matter;  we  abstract  the  element 
of  progressiveness,  and  we  call  it  Time. 
When  these  two  abstractions  combine, 
co-operate,  interact,  we  get  reality  again. 
It  is  like  Poynting's  theorem. 

The  only  way  to  refute  or  confuse  the 
theory  of  Evolution  is  to  introduce  the 


98  Presidential  Address 

subjectivity  of  time.  That  theory  in- 
volves the  reality  of  time,  and  it  is  in  this 
sense  that  Prof.  Bergson  uses  the  great 
phrase  "  Creative  Evolution.'* 

I  see  the  whole  of  material  existence  as 
a  steady  passage  from  past  to  future,  only 
the  single  instant  which  we  call  the  pre- 
sent being  actual.  The  past  is  not  non- 
existent however,  it  is  stored  in  our 
memories,  there  is  a  record  of  it  in  matter, 
and  the  present  is  based  upon  it;  the 
future  is  the  outcome  of  the  present,  and 
is  the  product  of  evolution. 

Existence  is  like  the  output  from  a 
loom.  The  pattern,  the  design  for  the 
weaving,  is  in  some  sort  "there"  already; 
but  whereas  our  looms  are  mere  machines, 
once  the  guiding  cards  have  been  fed 
into  them,  the  Loom  of  Time  is  compli- 
cated by  a  multitude  of  free  agents  who 
can  modify  the  web,  making  the  product 
more  beautiful  or  more  ugly  according  as 
they  are  in  harmony  or  disharmony  with 
the  general  scheme.  I  venture  to  main- 
tain that  manifest  imperfections  are  thus 
accounted  for,  and  that  freedom  could  be 


Continuity  99 

given  on  no  other  terms,  nor  at  any  less 
cost. 

The  ability  thus  to  work  for  weal  or  woe 
is  no  illusion,  it  is  a  reality,  a  responsible 
power  which  conscious  agents  possess; 
wherefore  the  resulting  fabric  is  not 
something  preordained  and  inexorable, 
though  by  wide  knowledge  of  character  it 
may  be  inferred.  Nothing  is  inexorable 
except  the  uniform  progress  of  time;  the 
cloth  must  be  woven,  but  the  pattern  is 
not  wholly  fixed  and  mechanically  cal- 
culable. Where  inorganic  matter  alone 
is  concerned,  there  everything  is  deter- 
mined. Wherever  full  consciousness  has 
entered,  new  powers  arise,  and  the  facul- 
ties and  desires  of  the  conscious  parts  of 
the  scheme  have  an  effect  upon  the  whole. 
It  is  not  guided  from  outside  but  from 
within,  and  the  guiding  power  is  imma- 
nent at  every  instant.  Of  this  guiding 
power  we  are  a  small  but  not  wholly  in- 
significant portion. 

That  evolutionary  progress  is  real  is 
a  doctrine  of  profound  significance,  and 
our  efforts  at  social  betterment  are  justi- 


ioo         Presidential  Address 

fied  because  we  are  a  part  of  the  scheme,  a 
part  that  has  become  conscious,  a  part 
that  realises,  dimly  at  any  rate,  what  it  is 
doing  and  what  it  is  aiming  at.  Planning 
and  aiming  are  therefore  not  absent  from 
the  whole,  for  we  are  a  part  of  the  whole, 
and  are  conscious  of  them  in  ourselves. 

Either  we  are  immortal  beings  or  we 
are  not.  We  may  not  know  our  destiny, 
but  we  must  have  a  destiny  of  some  sort. 
Those  who  make  denials  are  just  as  likely 
to  be  wrong  as  those  who  make  assertions: 
in  fact,  denials  are  assertions  thrown  into 
negative  form.  Scientific  men  are  looked 
up  to  as  authorities,  and  should  be  care- 
ful not  to  mislead.  Science  may  not  be 
able  to  reveal  human  destiny,  but  it  cer- 
tainly should  not  obscure  it.  Things  are 
as  they  are,  whether  we  find  them  out 
or  not;  and  if  we  make  rash  and  false 
statements,  posterity  will  detect  us — if 
posterity  ever  troubles  its  head  about 
us.  I  am  one  of  those  who  think  that  the 
methods  of  Science  are  not  so  limited  in 
their  scope  as  has  been  thought :  that  they 
can  be  applied  much  more  widely,  and  that 


Continuity  101 

the  Psychic  region  can  be  studied  and 
brought  under  law  too.  Allow  us  anyhow 
to  make  the  attempt.  Give  us  a  fair 
field.  Let  those  who  prefer  the  material- 
istic hypothesis  by  all  means  develop 
their  thesis  as  far  as  they  can;  but  let  us 
try  what  we  can  do  in  the  Psychical 
region,  and  see  which  wins.  Our  meth- 
ods are  really  the  same  as  theirs — the 
subject-matter  differs.  Neither  should 
abuse  the  other  for  making  the  attempt. 
Whether  such  things  as  intuition  and 
revelation  ever  occur  is  an  open  ques- 
tion. There  are  some  who  have  reason  to 
say  that  they  do.  They  are  at  any  rate 
not  to  be  denied  offhand.  In  fact,  it  is 
always  extremely  difficult  to  deny  any- 
thing of  a  general  character,  since  evi- 
dence in  its  favour  may  be  only  hidden 
and  not  forthcoming,  especially  not  forth- 
coming at  any  particular  age  of  the 
world's  history,  or  at  any  particular  stage 
of  individual  mental  development.  Mys- 
ticism must  have  its  place,  though  its  re- 
lation to  Science  has  so  far  not  been  found. 
They  have  appeared  disparate  and  discon- 


102          Presidential  Address 

nected,  but  there  need  be  no  hostility 
between  them.  Every  kind  of  reality 
must  be  ascertained  and  dealt  with  by 
proper  methods.  If  the  voices  of  Socrates 
and  of  Joan  of  Arc  represent  real  psy- 
chical experiences,  they  must  belong  to 
the  intelligible  universe. 

Although  I  am  speaking  ex  cathedra,  as 
one  of  the  representatives  of  orthodox 
science,  I  will  not  shrink  from  a  personal 
note  summarising  the  result  on  my  own 
mind  of  thirty  years'  experience  of  psy- 
chical research,  begun  without  predi- 
lection— indeed  with  the  usual  hostile 
prejudice.  This  is  not  the  place  to  enter 
into  detail  or  to  discuss  facts  scorned  by 
orthodox  science,  but  I  cannot  help  re- 
membering that  an  utterance  from  this 
chair  is  no  ephemeral  production,  for  it 
remains  to  be  criticised  by  generations 
yet  unborn,  whose  knowledge  must  inevi- 
tably be  fuller  and  wider  than  our  own. 
Your  President  therefore  should  not  be 
completely  bound  by  the  shackles  of 
present-day  orthodoxy,  nor  limited  to  be- 
liefs fashionable  at  the  time.  In  justice 


Continuity  103 

to  myself  and  my  co-workers  I  must 
risk  annoying  my  present  hearers,  not 
only  by  leaving  on  record  our  conviction 
that  occurrences  now  regarded  as  occult 
can  be  examined  and  reduced  to  order  by 
the  methods  of  science  carefully  and  per- 
sistently applied,  but  by  going  further 
and  saying,  with  the  utmost  brevity,  that 
already  the  facts  so  examined  have  con- 
vinced me  that  memory  and  affection  are 
not  limited  to  that  association  with  mat- 
ter by  which  alone  they  can  manifest 
themselves  here  and  now,  and  that  per- 
sonality persists  beyond  bodily  death. 
The  evidence — nothing  new  or  sensa- 
tional, but  cumulative  and  demanding 
prolonged  serious  study — to  my  mind 
goes  to  prove  that  discarnate  intelligence, 
under  certain  conditions,  may  interact 
with  us  on  the  material  side,  thus  indi- 
rectly coming  within  our  scientific  ken; 
and  that  gradually  we  may  hope  to  attain 
some  understanding  of  the  nature  of  a 
larger,  perhaps  etherial,  existence,  and 
of  the  conditions  regulating  intercourse 
across  the  chasm.  A  body  of  responsible 


104         Presidential  Address 

investigators  has  even  now  landed  on  the 
treacherous  but  promising  shores  of  a  new 
continent. 

Yes,  and  there  is  more  to  say  than  that. 
The  methods  of  science  are  not  the  only 
way,  though  they  are  our  way,  of  being 
piloted  to  truth.  "Uno  itinere  non  poles t 
perveniri  ad  tarn  grande  secretum." 

Many  scientific  men  still  feel  in  pug- 
nacious mood  towards  Theology,  because 
of  the  exaggerated  dogmatism  which  our 
predecessors  encountered  and  overcame 
in  the  past.  They  had  to  struggle  for 
freedom  to  find  truth  in  their  own  way; 
but  the  struggle  was  a  deplorable  neces- 
sity, and  has  left  some  evil  effects.  And 
one  of  them  is  this  lack  of  sympathy,  this 
occasional  hostility,  to  other  more  spiri- 
tual forms  of  truth.  We  cannot  really 
and  seriously  suppose  that  truth  began  to 
arrive  on  this  planet  a  few  centuries  ago. 
The  pre-scientific  insight  of  genius — 
of  Poets  and  Prophets  and  Saints — was 
of  supreme  value,  and  the  access  of  those 
inspired  seers  to  the  heart  of  the  universe 
was  often  profound.  But  the  camp  fol- 


Continuity  105 

lowers,  the  scribes  and  pharisees,  by 
whatever  name  they  may  be  called,  had 
no  such  insight,  only  a  vicious  or  a  foolish 
obstinacy;  and  the  prophets  of  a  new  era 
were  stoned. 

Now  at  last  we  of  the  new  era  have 
been  victorious,  and  the  stones  are  in  our 
hands.  But  for  us  to  imitate  the  old 
ecclesiastical  attitude  would  be  folly,  for 
it  cannot  be  sustained;  humanity  would 
ultimately  rise  against  us,  and  there 
would  come  yet  another  period  of  reac- 
tion, in  which  for  a  time  we  should  be 
worsted.  Through  the  best  part  of  two 
centuries  there  has  been  a  revolt  from 
religion,  led  by  Voltaire  and  other  great 
writers  of  that  age;  but  let  us  see  to  it 
that  the  revolt  ceases  when  it  has  gone  far 
enough.  Let  us  not  fall  into  the  mistake 
of  thinking  that  ours  is  the  only  way  of 
exploring  the  multifarious  depths  of  the 
universe,  and  that  all  others  are  worthless 
and  mistaken.  The  universe  is  a  larger 
thing  than  we  have  any  conception  of, 
and  no  one  method  of  search  will  exhaust 
its  treasures. 


io6         Presidential  Address 

Men  and  brethren,  we  are  trustees  of 
the  truth  of  the  physical  universe  as 
scientifically  explored:  let  us  be  faithful 
to  our  trust.  Genuine  religion  has  its 
roots  deep  down  in  the  heart  of  humanity 
and  in  the  reality  of  things.  It  is  not  sur- 
prising that  by  our  methods  we  fail  to 
grasp  it:  the  actions  of  the  Deity  make 
no  appeal  to  any  special  sense,  only  a 
universal  appeal;  and  our  methods  are, 
as  we  know,  incompetent  to  detect  com- 
plete uniformity.  There  is  a  Principle  of 
Relativity  here,  and  unless  we  encounter 
flaw  or  jar  or  change,  nothing  in  us  re- 
sponds ;  we  are  deaf  and  blind  therefore  to 
the  Immanent  Grandeur,  unless  we  have 
insight  enough  to  recognise  in  the  woven 
fabric  of  existence,  flowing  steadily  from 
the  loom  in  an  infinite  progress  towards 
perfection,  the  ever-growing  garment  of  a 
transcendent  God. 


THE   BRITISH  ASSOCIATION 
PRESIDENTIAL  ADDRESS 

1913 

EXPLANATORY  NOTES  BY  THE  PRESIDENT 
Page  i 

The  Chair  of  the  British  Association  at  Birmingham  was 
to  have  been  filled  by  Sir  William  White,  F.R.S.,  late  Chief 
Constructor  of  the  British  Navy,  who  had  been  made 
President  Elect  at  the  previous  Meeting  in  Dundee  in 
1912;  but  his  unexpected  death  in  the  spring  of  1913 
necessitated  a  fresh  election,  and  the  rule  of  the  Association 
against  a  local  president  was  broken  by  the  selection  of 
the  Principal  of  the  University  of  Birmingham  from  the 
short  list  of  those  whose  presidency  was  not  likely  to  be 
long  delayed.  This  explains  the  opening  paragraph. 

Pages  4,  13,  and  15 

The  quotations  are  from  a  set  of  four  lectures  which  Dr. 
Arthur  Schuster  gave  to  the  University  of  Calcutta  in 
1908,  now  published  by  the  Cambridge  University  Press 
under  the  title  The  Progress  of  Physics  during  jj  years 
(1875-1908). 

Page  7 

The    immediate    predecessor    spoken    of   is    Professor 
Schafer,  the  physiologist  whose  address  at  Dundee  in  1912 
107 


io8         Presidential  Address 

on  the  subject  of  Life,  and  on  the  possibility  of  artificially 
producing  it  or  of  formulating  its  origin,  excited  so  wide- 
spread an  interest.  The  penultimate  predecessor  is  Sir 
William  Ramsay,  the  chemist  who  presided  over  the  British 
Association  in  1911  at  Portsmouth  and  whose  experiments 
on  the  influence  of  radio-active  bodies  in  promoting  the 
transformation  of  one  element  into  others  have  been  re- 
ceived with  varying  degrees  of  caution.  The  nominated 
successor  spoken  of  is  Professor  Bateson,  the  biologist  who 
before  the  Birmingham  Meeting  was  nominated,  and  who 
at  Birmingham  was  elected,  to  preside  over  the  British 
Association  during  its  meeting  in  Australia,  and  who  is  a 
well-known  authority  on  heredity,  especially  from  the 
Mendelian  point  of  view. 

Page  10 

The  second  law  of  Thermodynamics  relates  to  the  work- 
ing power  of  heat,  and  asserts  the  fact  that  only  bodies  at 
high  temperature  can  be  usefully  employed  as  sources  of 
heat.  A  hydraulic  analogy  is  roughly  useful  as  a  first 
approximation:  water  at  high  level  can  be  used  to  drive 
machines  and  give  power,  but  water  at  average  or  sea  level 
cannot  be  so  used.  Hydraulic  working  power,  therefore, 
depends  on  two  things,  the  amount  of  available  water,  and 
its  head  or  height  above  zero  level.  So  it  is  also  with  heat. 
The  work  which,  by  a  heat  engine  like  a  steam  or  gas  or  oil 
engine,  can  be  extracted  from  it  depends  upon  its  quantity 
and  upon  its  temperature  above  some  practicable  zero,  say 
the  ordinary  average  temperature.  Only  in  the  impossible 
case  of  the  practical  zero  being  the  absolute  zero — a  fear- 
fully low  temperature  approximated  to  by  skilled  experi- 
menters but  not  actually  attained — could  all  of  any  given 
quantity  of  heat  be  utilised  in  the  performance  of  work. 

And  yet  heat  is  a  form  of  energy,  and  a  form  which  is 
liable  to  be  generated  as  a  bye-product  during  every  kind 


Explanatory  Notes  109 

of  material  activity.  Energy  is  protean  in  change  of  form, 
but  when  once  converted  into  heat  it  is  likely  to  retain 
that  form,  unless  some  ingenious  machine  is  employed 
to  transform  it  into  other  forms  of  energy  and  to  assist 
it  to  do  work,  as  when  the  vapour  of  boiling  water  is  en- 
abled to  pump  a  mine  or  drive  a  flywheel  by  aid  of  a  steam 
engine.  Moreover,  there  is  a  tendency  for  all  contiguous 
bodies,  unless  specially  prevented,  to  become  equal  in 
temperature, — a  condition  in  which  no  more  work  can  be 
obtained  by  any  thermal  process;  and  the  energy  is  then 
said  to  be  degraded  or  dissipated. 

Ultimately  therefore,  in  process  of  time,  it  has  been  sug- 
gested that  all  the  energy  of  the  Universe  may  be  expected 
to  take  the  low  form  of  heat  at  a  uniform  temperature,  *.  e. 
practically  at  an  exceedingly  low,  nearly  zero,  temperature 
— an  epoch  being  foreshadowed  at  which  every  activity 
will  thus  ultimately  cease. 

This  dismal  foreboding  is  not,  or  should  not  be,  set  for- 
ward with  any  certainty;  because  processes  whereby  energy 
may  be  pumped  up  again,  as  it  were,  from  lower  to  higher 
forms — through  the  agency  of  life  perhaps,  or  through  the 
agency  of  special  intelligence  for  which  the  crude  average 
terms  heat  and  temperature  have  no  dominating  meaning 
— can  be  imagined,  and  it  only  remains  for  us  to  discover 
them  in  action  somewhere. 

A  description  of  how  such  intelligences  could  act  was 
first  given  by  Clerk  Maxwell,  and  was  vividly  elaborated 
by  Lord  Kelvin.  They  are  known  as  "  Maxwell's  demons." 
Some  biologists  have  suspected  the  real  existence  of  such, 
agents,  in  nitrifying  bacteria  and  the  like;  and  although  no 
definite  discovery  of  agencies  which  will  reverse  results 
attributed  to  the  second  law  of  Thermodynamics  has  yet 
been  made,  it  would  be  a  mistake  to  limit  the  possibility  of 
discovery. 

And  anyhow  the  material  universe  is  manifestly  in  full 
blast  at  present;  it  has  not  by  any  means  reached  the  stage 


no         Presidential  Address 

of  decadence  when  the  sun  and  all  bodies  are  at  one  and  the 
same  temperature  and  when  every  activity  has  ceased. 
(Cf.  page  59.)  The  Universe  is  undoubtedly  still  a  going 
concern,  and  yet  it  has  presumably  already  lasted  an 
infinite  time — for  all  we  know  to  the  contrary. 

As  to  the  first  law  of  Thermodynamics,  that  is  merely 
the  conservation  of  energy  applied  to  heat.  It  was  the 
experimental  and  quantitative  inclusion  of  heat  as  a  form 
of  energy  which  allowed  the  law  of  Conservation  of  Energy 
to  be  definitely  formulated  by  Joule. 

Page  II 

The  most  important  of  Newton's  Laws  of  Motion  is 
that  the  acceleration  of  a  body  is  proportional  to  the 
resultant  force  which  acts  upon  it  and  is  in  the  same  di- 
rection. The  ratio  of  force  to  acceleration  is  called  the 
mass  or  inertia  of  the  body,  and  in  ordinary  Newtonian 
Mechanics  it  is  treated  as  constant.  There  is  a  sense  in 
which  the  remarkable  constancy  of  mass,  no  matter  what 
happens  to  it, — in  the  way  of  boiling,  freezing,  decom- 
position, burning,  or  solution, — is  synonymous  with  the 
fundamental  postulate  of  the  conservation  of  matter.  But 
there  are  other  senses  in  which  it  is  not  difficult  to  allow  for 
a  possible  variation  of  mass  of  a  moving  body,  and  hence  to 
get  a  variable  ratio  between  the  force  applied  to  it  and  the 
acceleration  produced. 

Recently  it  has  been  found  that  electrons  moving  near 
the  speed  of  light  have  an  increased  mass.  The  result  has 
been  arrived  at  both  theoretically  and  experimentally. 
It  was  in  fact  first  predicted  mathematically  and  after- 
wards confirmed  experimentally,  and  may  be  taken  as 
quite  undoubted. 

Mass  therefore  becomes  a  function  of  speed.  At  all 
ordinary  speeds  it  is  practically  constant;  but  at  excessive 
speeds,  far  beyond  that  of  a  cannon  ball,  it  begins  very 


Explanatory  Notes  in 

slightly  to  increase;  at  speeds  expressed  in  thousands  of 
miles  per  second  it  begins  to  increase  faster;  and  at  the 
speed  of  light  it  suddenly  appears  to  become  infinite — 
whatever  that  may  mean.  Hence  there  are  some  who 
think  that  bodies  can  never  move  through  the  ether  faster 
than  the  velocity  of  light. 

Page  12 

In  Euclidian  Geometry  only  one  straight  line  can  be 
drawn  through  a  given  point  parallel  to  another  straight 
line.  That  no  more  than  one  is  possible  has  never  been 
proven:  it  was  a  definite  postulate  or  axiom  made  by 
Euclid,  but  it  seemed  incapable  of  proof.  Within  recent 
times  pure  mathematicians  have  found  it  possible  to  devise 
other  more  general  systems  of  Geometry,  in  which  two  or 
many  such  lines  can  be  drawn.  Thus  Euclidian  Ge- 
ometry, which  still  appears  to  suit  our  own  spatial  expe- 
rience very  well,  can  be  regarded  as  a  special  case  of  more 
generalised  and  comprehensive  theoretical  systems. 

Abstract  propositions  may  be  absolutely  and  completely 
true:  practical  experience  can  approximate  to  them  more 
or  less  precisely — in  Geometry  more  precisely  than  in  any 
other  subject.  The  relation  between  our  systems  of 
thought  on  the  one  hand,  and  our  actual  experience  on  the 
other,  is  well  illustrated  by  the  following  quotation  from 
Poincare": — 

"The  principles  of  geometry  are  not  experimental  facts. 
.  .  .  Euclid's  postulate  cannot  be  proved  by  experiment. 
...  If  Lobatschewsky's  geometry  is  true,  the  parallax  of  a 
very  distant  star  will  be  finite.  If  Riemann's  is  true,  it  will 
be  negative.  These  are  results  which  seem  within  the 
reach  of  experiment,  and  some  have  hoped  that  astronomi- 
cal observations  may  enable  us  to  decide  between  the 
geometries.  But  what  we  call  a  straight  line  in  astronomy 
is  simply  the  path  of  a  ray  of  light.  If,  therefore,  we  were 


ii2         Presidential  Address 

to  discover  negative  parallaxes,  or  to  prove  that  all  par- 
allaxes are  higher  than  a  certain  limit,  we  should  have  a 
choice  between  two  conclusions :  we  could  give  up  Euclid- 
ean geometry,  or  modify  the  laws  of  optics,  and  suppose 
that  light  is  not  rigorously  propagated  in  a  straight  line. 
It  is  needless  to  add  that  everyone  would  look  upon  this 
solution  as  the  more  advantageous.  Euclidean  geometry, 
therefore,  has  nothing  to  fear  from  fresh  experiments. " 

Page  1 6 

By  "Euclid's  Postulate"  is  meant  the  famous  postulate 
or  axiom  above  referred  to.  It  is  commonly  called  ' '  Axiom 
12"  in  textbooks  of  Euclid  elements.  It  lies  at  the  base  of 
all  his  doctrine  of  parallels,  and  it  leads  direct  to  the  con- 
clusion that  the  three  angles  of  a  triangle  are  together 
equal  to  two  right  angles.  In  fact  it  is  another  form  of 
stating  that  proposition. 

Page  17 

The  "Preface"  referred  to  is  the  Introduction  by  Sir 
Joseph  Larmor,  M.P.,  Lucasian  Professor  of  Mathematics 
in  the  University  of  Cambridge,  to  the  English  translation 
of  Pomcare"'s  book  called  Science  and  Hypothesis  (Scott). 

Page  28 

Boyle's  Law  is  that  the  volume  of  a  gas  varies  inversely 
with  the  pressure  to  which  it  is  subjected.  It  is  a  natural 
consequence  of  the  kinetic  theory  of  gases  in  its  simplest 
form;  but,  when  considered  strictly,  it  is  seen  to  involve 
the  assumption  that  the  gaseous  particles  are  infinitely 
small — so  small  that  they  can  never  become  the  least 
crowded,  however  great  the  pressure, — and  further  that 
there  is  no  attractive  force  or  incipient  cohesion  acting 


Explanatory  Notes  113 

between  them,  so  that  never  would  the  effect  of  pressure 
be  assisted  by  the  action  of  internal  forces.  In  all  actual 
gases  the  particles  have  some  intrinsic  size  of  their  own; 
and  cohesion  becomes  sooner  or  later  conspicuous,  so  that 
ultimately  liquefaction  is  possible.  The  further  a  gas  is 
from  showing  any  sign  of  molecular  cohesion,  the  more 
'  nearly  is  it  considered  "perfect"  as  a  gas.  An  imperfect 
gas  exhibits  already  an  incipient  tendency  towards  ulti- 
mate liquefaction.  A  corrected  form  of  Boyle's  law,  applic- 
able not  only  to  imperfect  gases  but  also  to  liquids,  was 
devised  by  the  great  Dutch  physicist  Van  der  Waals,  whose 
treatment,  though  not  even  yet  finally  accurate,  was  pro- 
foundly interesting  and  instructive. 

Page  19 

The  way  in  which  Kepler  discovered  his  famous  laws, 
from  elaborate  discussions  of  the  planetary  observations  of 
Tycho  Brahe,  is  explained  in  many  books:  among  others, 
in  the  author's  own  semi-popular  volume  called  Pioneers 
of  Science  (Macmillan). 

Page  21 

The  familiar  behaviour  of  a  wet  sandy  beach,  when 
walked  over,  is  very  curious;  the  pressure  of  a  foot  dries  it, 
while  relaxation  of  pressure  moistens  it.  In  other  words, 
pressure  applied  to  a  collection  of  granular  particles  tends 
to  increase  the  spaces  between  them,  and  so  enables  them 
to  hold  more  water  in  their  interstices.  Relaxation  and 
constraint  allow  the  molecules  to  adjust  themselves  closer 
together,  and  so  to  squeeze  some  of  the  liquid  out  again. 
Just  opposite  to  the  behaviour  of  a  sponge. 

It  was  on  a  highly  developed  superstructure  based  on 
this  foundation  that  Professor  Osborne  Reynolds  of  Man- 
chester devised  his  scheme,  wherein  "the  ether"  was  sup- 

8 


H4         Presidential  Address 

posed  to  consist  of  rigid  granules  in  contact,  and  where 
"matter  "  was  the  hollows  or  cavities  or  regions  of  greater 
interstitial  capacity  existing  among  them.  These  regions 
could  readily  travel  about  from  one  part  of  the  granular 
structure  to  another;  and  this  represented  the  motion  of 
matter  in  the  scheme.  Such  an  ether  is  very  unlike  any 
contemplated  by  the  author. 

Page  22 

In  the  Physical  Review  for  August,  1913,  Professor  R. 
A.  Millikan  summarises  the  results  of  most  recent  and 
trustworthy  determinations  of  molecular  magnitudes,  and 
among  them  of  Avogadro's  constant.  It  may  be  conven- 
ient to  quote  some  of  them  here: — 

Unit  of  electric  charge,  e  =4.774X10  — I0  electrosta- 
tic units. 

Number    of    molecules 

per  gramme  molecule,  N  =6.062  Xioa*. 
Molecules  per  cubic 
centimetre  of  gas  at  o° 
and  76,  n  =2.705  Xio1'. 

Planck's  constant  h  =6.62  Xio  —  2?cgs. 

The  number  of  H2O  molecules  in  a  cubic  centimetre,  or 
say  15  grains,  of  water  is  therefore  -33Xio23;  and  the 
number  of  atoms  io23. 

Now  io23  cubic  centimetres  of  water  weigh  lo1?  tons, 
=  io8  cubic  kilometres, 
=25  million  cubic  miles, 

which  would  form  an  ocean  6000  miles  long,  2000  miles 
wide,  and  2  miles  deep, — corresponding  therefore  very 
fairly  to  the  North  Atlantic  Ocean. 

Page  23 

For  a  further  discussion  of  incommensurable  quantities, 
and  of  the  impossibility  of  expressing  the  majority  of 


Explanatory  Notes  115 

physical  ratios  by  any  actual  number,  the  author's  text- 
book of  Arithmetic  and  Algebra  for  General  Readers, 
called  Easy  Mathematics  (Macmillan),  may  be  referred  to, 
in  chapter  xx  and  elsewhere. 

Page  26 

By  the  "degrees  of  freedom"  of  a  body  are  meant  the 
independent  modes  of  motion  of  which  it  is  susceptible. 
A  rigid  body  has  six  degrees  of  freedom,  which  can  be  thus 
enumerated: — a  translation  or  locomotion  in  each  of  three 
directions,  the  three  dimensions  of  space,  up  and  down,  to 
and  fro,  right  and  left;  and  three  rotations,  viz.,  rotation 
about  each  of  these  three  directions  considered  as  axes. 
A  particle  however — meaning  a  body  of  no  size — has  only 
three  degrees  of  freedom;  it  can  only  move  in  the  sense  of 
locomotion,  it  cannot  spin ;  or  rather  it  may  spin  as  much  as 
it  likes  and  no  one  will  care,  its  spinning  will  consume  no 
energy.  A  perfectly  smooth  sphere  is  in  much  the  same 
predicament;  while  a  smooth  dumb-bell  has  five  degrees  of 
freedom,  one  of  its  rotations  being  ineffective.  But  a  tun- 
ing fork,  or  body  susceptible  of  vibration,  has  many^ore 
degrees  of  freedom  than  a  rigid  body  can  have;  and  inas- 
much as  molecules  appear  susceptible  of  vibration,  as 
evidenced  by  the  spectra  they  emit,  it  might  be  supposed 
that  during  their  ordinary  mutual  collisions  in  a  perfect 
gas  many  of  these  vibratory  movements  would  be  called 
out  and  take  part  in  the  action.  If  so,  they  would  be 
entitled  to  some  of  the  energy.  Indeed  a  mechanical 
theory  of  Clerk  Maxwell's  proves  that  after  a  great  number 
of  prefectly  random  collisions  all  the  energy  imparted  to  a 
group  of  similar  bodies  will  be  equally  shared,  on  an  aver- 
age, among  all  the  degrees  of  freedom  which  they  possess 
(strictly  speaking,  among  all  the  degrees  of  freedom  which 
are  effective  during  collision).  If,  therefore,  a  given 
quantity  of  energy,  say  heat,  is  imparted  to  a  gas,  it  might 


n6         Presidential  Address 

be  expected  that  it  would  be  split  up  into  so  many  equal 
fractions  that  the  translatory  energy  of  the  molecules 
— i.e.  the  motion  upon  which  "temperature"  depends — 
would  be  increased  to  only  an  insignificant  extent.  But  it 
is  not  so.  Experiment  on  the  velocity  of  sound  through 
various  gases  shows  that  the  energy  imparted  by  acoustic 
compression  raises  the  temperature  quite  decidedly,  and  is 
therefore  only  divided  into  quite  a  moderate  number  of 
parcels.  The  number  is  found  to  be  3  for  monatomic 
molecules,  which  therefore  to  that  extent  behave  like 
smooth  spheres;  5  for  diatomic  molecules,  which  therefore 
behave  like  smooth  dumb-bells;  and  6  for  molecules  con- 
sisting of  3  or  more  atoms,  which  therefore  behave  like  the 
general  rigid  body. 

How  it  can  come  about  that  vibratory  degrees  of  free- 
dom are  excluded  from  the  sharing,  even  after  the  lapse  of 
some  time,  has  long  been  a  subject  of  controversy;  and  the 
fact  that  it  is  so  has  thrown  doubt  upon  the  equi-partition 
theorem  itself.  The  answer  suggested  by  Professor  Planck, 
the  eminent  physicist  of  Berlin,  is  that  fractions  of  a  unit 
of  energy  cannot  exist,  so  that  the  attempt  to  subdivide  a 
given  portion  of  energy  into  an  immense  number  of  frac- 
tions must  fail;  only  those  degrees  of  freedom  that  can  re- 
ceive a  whole  unit  can  be  effective:  it  is  a  case  of  all  or  none, 
and  those  subsidiary  modes  of  motion  that  can  only  receive 
a  fraction  will  not  get  any. 

This  is  an  exceedingly  crude  and  partial  account  of  the 
initial  stages  of  a  large  and  complex  subject,  which  has 
been  highly  developed  and  is  arousing  much  interest.  The 
unit  of  energy  called  "Planck's  constant  "enters  into  very 
many  parts  of  Physics,  and  appears  to  be  a  reality,  how- 
ever it  be  accounted  for;  but  I  consider  that  the  explana- 
tion is  to  be  found  in  specific  properties  of  matter,  and  not 
in  the  really  atomic  character  of  energy  itself. 

The  fact  that  vibratory  molecular  energies  are  not  ef- 
fective in  an  ordinary  gas,  are  not  evoked  by  ordinary 


Explanatory  Notes  117 

molecular  collision,  seems  to  be  clear;  but  the  cause  of  it 
may  be  put  differently  by  different  people.  (See  pages  37 
and  38.) 

Pages  29  and  30 

The  reference  here  is  to  the  extreme  doctrine  of  Professor 
Weismann,  at  one  time  urged  upon  us,  that  no  character- 
istic acquired  during  the  life  of  an  individual  or  series  of 
individuals  could  be  transmitted  by  inheritance.  The 
truth  underlying  this  doctrine  is  that  unless  the  sperm  or 
germ  cells  are  affected,  mere  alteration  of  body  tissue  is 
ineffective  for  anything  beyond  the  individual.  That  is 
manifest.  The  cells  which  transmit  vitality  to  the  off- 
spring must  naturally  be  modified  if  modifications  are  to  be 
conveyed  by  them.  But  it  is  unreasonable  to  suppose  that 
deep-seated  changes  in  somatic  or  bodily  structure  can  be 
caused  without  at  least  running  the  risk  of  affecting  the 
more  permanent  transmission  cells  also  to  some  extent. 
Mere  defective  or  injudicious  nourishment  may  have  its 
due  influence  in  this  direction.  A  microscope  may  not 
show  any  difference,  some  other  test  must  be  applied ;  and 
by  far  the  most  sensitive  test  for  the  actual  occurrence  of 
such  alteration  consists  in  observing  whether  inheritance  is 
really  affected  or  not.  On  that  question  specific  experi- 
ments are  desirable  and  ought  to  be  made.  If  surround- 
ings have  no  effect  on  the  race,  except  a  survival  effect, — 
if  the  individual  can  acquire  nothing  which  is  transmissible, 
— it  will  be  very  extraordinary;  but  the  test  can  only  be 
made  by  direct  experiment  and  observation.  Hence  we 
are  thrown  back  on  actual  experience  in  every  instance, 
and  we  cannot  generalise  and  say  that  no  sort  of  character 
acquired  by  the  individual  can  be  handed  down  to  his  or 
her  descendants.  What  I  suggest  in  the  text  is  that  the 
discontinuity  between  reproductive  and  bodily  cells  is  not 
likely  to  be  as  complete  as  that. 


n8         Presidential  Address 

Page  34 

'  Matter  is  essentially  that  which  moves.  We  are 
acquainted  with  no  portion  of  matter  which  is  really 
stationary.  A  statement  of  the  speed  and  direction  of 
motion  can  be  included  among  the  elements  of  description 
of  any  piece  of  matter.  Ether  in  the  same  sense  cannot  be 
moved,  but  it  can  be  strained.  It  is  strained  when  a  bow 
is  bent;  and  it  is  also  strained,  though  less  obviously,  when 
a  weight  is  raised,  or  when  gunpowder  is  kept  without  the 
release  afforded  by  pulling  the  trigger.  In  all  these  cases 
particles  of  matter  are  put  into  constrained  positions  with 
reference  to  each  other,  and  the  seat  of  the  static  energy 
involved  is  the  ether  between  and  near  the  particles. 
When  it  is  released  kinetic  energy  results,  for  the  matter  is 
then  more  or  less  violently  moved.  Kinetic  energy  belongs 
to  matter,  Static  or  Potential  to  ether.  The  arguments 
for  high  density  of  ether,  and  for  the  extraordinarily  filmy 
or  gossamer-like  character  of  matter  compared  to  it,  will 
be  found  in  my  small  book,  The  Ether  of  Space,  (Harper 
&  Bros.). 

Page  37 

Part  of  the  basis  of  Planck's  theory  of  quanta,  or  indivisi- 
ble units  of  energy,  is  given,  in  rudimentary  fashion,  in 
the  note  to  Page  26. 

Page  41 

The  Brownian  movement,  long  known  as  a  constant 
fidget  of  minute  particles  suspended  in  liquid  and  viewed 
through  a  high-power  microscope,  has  acquired  great 
interest  of  late  by  the  discovery  that  all  the  laws  of  gases 
apply  to  those  visible  material  aggregates,  consisting  as  they 
must  of  billions  of  atoms,  as  well  as  to  the  almost  infinitely 
smaller  and  quite  invisible  things,  the  atoms  and  molecules 


Explanatory  Notes  119 

themselves.  An  interesting  account  of  all  these  matters 
will  be  found  in  a  scientific  book  by  M.  Jean  Perrin,  Pro- 
fessor of  Physical  Chemistry  in  the  University  of  Paris, 
which  has  been  translated  into  English  by  Mr.  Soddy, 
F.R.S.,  and  published  by  Taylor  &  Francis  under  the  title: 
Brownian  Movement  and  Molecular  Reality. 

Pages  43  to  64 

It  is  as  difficult  to  convey  to  general  readers  some  idea  of 
the  Principle  of  Relativity,  and  its  virtual  supersession 
of  the  Ether,  as  it  was  to  explain  about  the  equi-partition 
of  energy  and  quanta,  but  a  rough  attempt  may  again  be 
made.  It  has  long  been  a  moot  point  whether  the  Ether 
was  or  was  not  carried  forward  to  any  extent  by  moving 
matter.  The  question  was  discussed  mathematically  by 
Fresnel  at  the  beginning  of  last  century;  and  Fizeau  found 
experimentally  that  light  travelled  quicker  down  running 
water  than  when  it  travelled  against  the  stream — about 
half  (more  accurately  y/i6ths)  of  the  speed  of  the  water 
being  added  to  the  light,— quite  in  accordance  with  the 
teachings  of  Fresnel.  But  whether  this  sort  of  effect 
could  be  detected  in  the  immediate  neighbourhood  of 
moving  matter,  without  going  actually  inside  it,  was  quite 
unknown;  and  in  and  about  1892  and  subsequent  years  at 
Liverpool  I  made  a  serious  attempt  to  examine  the  ques- 
tion experimentally.  The  experiments  are  described  in  the 
Philosophical  Transactions  of  the  Royal  Society  for  1893 
and  1897,  and  the  conclusion  is  that  when  a  mass  of  iron 
or  steel  is  spinning  so  fast  that  it  is  liable  to  fly  to  pieces, 
and  when  light  is  sent  by  mirrors  round  and  round  many 
times  in  its  immediate  neighbourhood, — so  close  as  to  be 
actually  grazing  the  spinning  disks  in  some  instances, — 
not  the  slightest  effect  of  acceleration  is  manifested  by  the 
beam  of  light,  however  delicately  it  be  tested  by  means  of 
interference  bands.  Interference  is  arranged  between 


120         Presidential  Address 

beams  which  have  travelled  half  with  and  half  against 
the  motion,  for  many  yards;  but,  after  spurious  results  are 
allowed  for,  there  is  no  shift  of  the  bands;  proving  that  the 
velocity  is  not  affected  by  so  much  as  one  tenth  of  one  per 
cent,  of  the  velocity  of  the  moving  matter.  Practically  we 
may  say  that  the  Ether  of  space  is  never  carried  forward — 
— presumably  not  even  by  a  planet; — for  the  Fizeau  effect, 
properly  interpreted,  means  the  same  thing. 

Professor  Michelson  of  Chicago,  however,  one  of  the 
most  brilliant  experimental  physicists  in  America — which 
is  saying  a  good  deal — tried  a  totally  different  experiment, 
examining  whether  light  sent  to  and  fro  over  a  fixed  dis- 
tance in  the  direction  of  the  earth's  planetary  motion 
through  space,  took  any  longer  on  its  double  journey  than 
it  did  when  sent  to  and  fro  over  the  same  distance  across 
the  motion.  The  result  was  likewise  negative :  no  difference 
could  be  perceived;  though  the  delicate  experiment  was 
performed  with  the  utmost  care  and  skill,  and  was  after- 
wards repeated  still  more  elaborately  by  Professor  Michel- 
son  and  Mr.  Morley  in  collaboration.  This  negative 
result,  however,  is  in  apparent  or  superficial  opposition 
to  the  other  negative  result :  it  seemed  difficult  to  suppose 
that  they  could  both  be  true.  Because  if  the  Ether  is  not 
carried  forward  by  the  earth  at  all,  it  must  be  relatively 
streaming  past  the  earth  with  a  speed  of  many  miles  per 
second,  as  many  as  30  sometimes ;  and  accordingly  an  effect 
ought  to  be  obesrved.  The  negative  result  of  Michelson, 
therefore,  superficially  suggests  that  the  Ether  in  the 
neighbourhood  of  the  earth  is  stagnant — which  in  this 
case  is  the  opposite  of  stationary — i.e.  that  it  clings  to  the 
earth  and  is  carried  forward  by  it.  Many  difficulties 
would  arise  if  that  were  true,  and  the  theory  of  ordinary 
astronomical  aberration  would  be  complicated;  the  Ether 
would  no  longer  be  behaving  as  a  perfect  fluid,  but  would  be 
exhibiting  what  is  called  viscosity.  Planets  could  hardly 
move  through  it  without  resistance,  and  astronomical 


Explanatory  Notes  121 

theory  would  have  to  be  overhauled.  Moreover,  my 
experiment  with  steel  disks,  designed  to  detect  a  trace  of 
viscosity,  failed  to  show  any:  in  fact  negatived  the  idea. 
So  the  FitzGerald-Lorentz  hypothesis  was  devised  in 
order  to  explain  the  negative  result  of  Professor  Michelson 
in  another  way,  by  postulating  a  minute  change  of  shape 
or  distortion  of  all  bodies  as  they  move  through  the  Ether 
of  space  at  any  excessive  speed ;  and  there  is  a  great  deal 
to  be  said  in  favour  of  such  a  hypothesis.  Some  physicists, 
however,  consider  it  only  a  hyper-ingenious  and  imagin- 
ative device  of  evading  awkward  and  irreconcilable  facts. 
Many  other  experiments  have  been  made  to  detect  the 
effect  of  an  etherial  movement  relatively  to  the  earth; 
and  they  have  all  uniformly  failed.  So  at  length  Professor 
Einstein  first,  and  now  many  others,  have  supposed  that 
the  Universe  is  so  adjusted  that  an  observation  of  this 
kind  is  for  ever  impossible.  They  boldly  make  the  postu- 
late or  axiom  that  although  motion  of  matter  with  respect 
to  matter  is  readily  perceived,  motion  of  matter  with  re- 
spect to  ether  is  impossible  to  observe  and  is  in  fact  mean- 
ingless. They  formulate  the  principle  that  nothing 
but  relative  motion  of  pieces  of  matter  with  respect-to 
each  other  can  ever  be  detected,  and  that  no  change 
in  the  velocity  of  light  can  ever  be  observed  except  when 
there  is  relative  motion  of  matter.  This  principle,  en- 
throned as  the  Principle  of  Relativity,  has  become  the 
foundation  of  a  mathematical  erection,  with  far-reaching 
and  in  some  cases  surprising  and  almost  paradoxical  con- 
sequences, affecting  the  going  of  clocks  and  even  the  nature 
of  Time. 

The  difficult  part  of  the  theory  of  Relativity  is  connected 
with  the  deduction  of  all  these  remarkable  consequences: 
the  fact  that  motion  with  respect  to  the  ether  is  difficult 
to  observe,  together  with  the  familiar  fact  of  the  extreme 
ease  of  observing  the  relative  motion  of  pieces  of  matter 
with  respect  to  each  other,  constitutes  the  superficial  and 


1 22          Presidential  Address 

primary  foundation  for  the  Principle  of  Relativity.  The 
Principle  goes  on  to  translate  difficulty,  in  the  first  case,  into 
impossibility,  and  then  to  make  elaborate  mathematical 
deductions. 

The  mode  in  which  I  would  explain  the  admitted  fact 
that  nothing  but  relative  motion  of  pieces  of  matter  has  so 
far  been  observed,  is  indicated  on  pages  47  et  seq.;  the  cause 
of  all  the  negative  experimental  results,  on  which  founda- 
tion of  the  Principle  rests,  is  to  be  found  in  the  complete 
uniformity  of  the  ether  and  in  its  universal  activity  and 
prevalence.  This  has  led  to  the  Principle  which  virtually 
denies  its  existence.  The  last  thing  that  a  deep-sea  fish 
could  discover  would  be  water.  (See  also  page  106.) 

Page  46 

The  second  paragraph  on  this  page  is  another  refer- 
ence to  my  Ether-gripping  experiment,  referred  to  in  the 
above  note  and  page  35,  and  briefly  described  in  my  book 
The  Ether  of  Space.  The  word  "  hope  "  can  only  be  used 
in  a  special  sense  in  connection  with  any  experiment:  the 
object  of  that  experiment  was  of  course  to  ascertain 
whether  the  ether  is  to  any  degree  attached  to  moving 
matter  or  not.  I  was  not  aware  of  having  any  expectation 
of  a  positive  result.  What  I  was  anxious  about  was  to 
make  sure  of  a  definite  answer  one  way  or  the  other. 

Page  49 

Rotation  of  an  isolated  non-rigid  body  can  be  detected 
by  its  bulging  under  centrifugal  force:  as  when  a  bucket  is 
twisted  the  liquid  surface  becomes  parabolic.  Again,  the 
non-spherical  shape  of  the  earth  or  of  Jupiter  is  immedi- 
ately connected  with  their  periods  of  rotation,  i.e.,  with 
the  length  of  their  respective  "days.  The  oblateness  of  the 
earth  was  thus  quantitatively  predicted  by  Newton  long 


Explanatory  Notes  123 

before  it  was  geodetically  observed  by  accurate  surveying. 
See,  for  instance,  Pioneers  of  Science,  previously  referred 
to. 

Page  54 

The  pressure  exerted  by  light  was  predicted  by  Clerk 
Maxwell,  and  by  Bartoli,  and  first  observed  by  Nicholls 
and  Hull.  The  consequent  or  associated  momentum 
conveyed  by  a  wave  front,  and  a  number  of  the  effects 
deducible  from  this  process,  have  been  worked  out  most 
instructively  by  Professor  J.  H.  Poynting,  who  has  pub- 
lished a  little  book  on  the  subject  called  The  Pressure  of 
Light  (S.P.C.K.). 

Pages  62  and  63 

The  Michelson-Morley  experiment  detects  no  difference 
between  a  journey  to  and  fro  and  a  journey  right  and  left, 
if  one  is  facing  the  hypothetical  ether  stream  presumably 
caused  relatively  to  the  earth  by  its  rapid  motion  through 
space,  and  if  one  is  sending  a  beam  of  light  in  these  direc- 
tions by  means  of  mirrors  mounted  on  some  rigid  body, 
such  as  a  block  of  stone  or  metal.  (See  also  Note  to  pp. 
43-64.)  But  elementary  arithmetic  shows  that  it  ought 
to  take  slightly  longer,  going  up  and  down  the  stream, 
than  there  and  back  across  it.  Hence,  either  there  is  no 
such  ether  stream,  or  else  the  block  on  which  the  mirrors 
and  other  optical  appliances  are  mounted  changes,  so  as  to 
be  shorter  by  a  compensating  amount  in  the  direction  of 
motion  as  compared  with  its  breadth  in  the  transverse 
direction.  The  required  change  is  exceedingly  small, 
equivalent  to  a  shrinkage  of  three  inches  in  8000  miles, 
yet  on  the  electric  theory  of  matter  something  of  this  mag- 
nitude almost  certainly  ought  to  occur.  This  is  the  famous 
FitzGerald-Lorentz  hypothesis,  referred  to  in  the  text. 
(See  pp.  53  and  64;  also  my  book  Electrons,  chapter 
xvi.,  about  cohesion.) 


124         Presidential  Address 

The  algebraic  expression  given  on  page  64  for  the 
amount  of  the  change  is  not  quite  the  usual  orthodox 
expression  for  it;  but  it  is  one  which  I  have  reason  for 
putting  forward,  and  is  not  a  misprint. 

Page  76 

The  long-standing  puzzle  as  to  how  vegetable  sap  is 
raised  against  gravity  from  the  ground  to  the  tops  of  the 
highest  trees  has  been  practically  settled  by  recent  workers, 
notably  by  Professor  H.  H.  Dixon  of  Trinity  College, 
Dublin,  who  has  made  a  clear  statement  of  the  way  in 
which  osmosis,  or  molecular  diffusion  through  semi-per- 
meable membranes,  enables  it  to  occur. 

Page  80 

Higher  plants  can  only  assimilate  inorganic  material 
after  it  has  been  first  incorporated  into  more  lowly  organ- 
isms. Harsh  treatment  of  a  soil  is  found  helpful  to  the 
beneficent  and  manuring  bacteria;  for,  being  low  in  the 
scale  of  existence,  they  are  hardier  and  more  resistant  to 
hostile  influences  than  the  still  microscopic  foes  which  feed 
upon  them.  Wherefore  treatment  which  slays  the  one 
indirectly  benefits  the  other.  This  explanation  is  not  yet 
proven,  but  the  facts  suggest  it  as  likely. 

Page  80 

The  larval  stage  of  the  mosquito  is  passed  in  water,  and 
the  larvae  cling  to  and  perforate  the  surface  in  order  to 
breathe.  If  the  surface  is  oiled  the  surface  tension  is 
diminished,  the  surface  does  not  support  them,  and  they 
keep  on  sinking  till  they  drown.  But  not  every  puddle  or 
dribble  of  liquid  can  be  oiled,  and  so  breeding  places  can  be 
guarded  against  partly  by  drainage  and  partly  by  allowing 
no  unperf orated  vessel  to  remain  as  a  trap  for  accumulated 
water. 


Explanatory  Notes  125 

Page  84 

The  ancient  arguments  of  Zeno  and  other  philosophers 
are  of  the  nature  of  a  reductio  ad  absurdum,  and  were  di- 
rected against  the  trivial  arguments  of  certain  opposing 
philosophers.  The  contention  that  motion  cannot  occur 
because  an  object  must  be  in  either  one  place  or  another, 
and  the  contention  that  a  quick  runner  cannot  pass  a  slow 
one  because  the  space  between  them  is  infinitely  subdivis- 
ible and  some  time  is  needed  to  cover  every  division  were 
not  put  forward  as  statements  of  fact  absurdly  contrary  to 
experience,  but  as  arguments  in  favour  of  continuity  of 
space  and  against  a  static  idea  of  time.  All  these  ancient 
paradoxes  are  really  ingenious  weapons  of  dialectic,  and 
are  not  to  be  taken  as  a  sign  of  philosophic  stultification,  as 
unfortunately  they  sometimes  are. 

Page  86 

By  a  catalytic  agent  is  signified  in  Chemistry  something 
which  promotes  a  process  or  chemical  change  without 
taking  part  in  it:  that  is  to  say,  a  material  substance  which 
by  its  presence  facilitates  a  reaction  while  itself  remaining 
unchanged,  apparently,  or  at  any  rate  ultimately,  inert. 
Such  instances  are  very  common;  one  of  the  best  known 
being  the  action  of  manganese  dioxide  in  the  liberation  of 
oxygen  from  potassic  chlorate.  If  every-day  illustrations 
are  helpful,  a  broker  may  be  called  a  catalytic  agent  in  a 
Stock  Exchange  transaction;  and  the  same  epithet  might 
be  applied  to  a  parson  at  a  wedding. 

Now  in  the  various  interactions  which  occur  between  the 
two  great  conserved  entities,  energy  and  matter,  life  and 
living  bodies  seem  to  act  in  a  catalytic  fashion;  for  they 
contribute  no  energy,  but  they  direct  it,  and  thereby  facili- 
tate operations  that  without  their  aid  would  have  been 
difficult  or  impossible.  The  simple  act  of  lifting  a  fallen 


126         Presidential  Address 

body  may  be  adduced  as  an  instance  of  such  an  operation, 
without  ascending  to  the  more  striking  case  of  engineering 
works;  while  in  a  chemical  or  physical  or  biological  labora- 
tory innumerable  so  to  speak  "unnatural"  things  are  done, 
and  the  ordinary  operations  of  nature  designedly  inter- 
fered with. 

Page  91-92 

Some  examples  of  purely  inorganic  crystallisation, 
especially  when  viewed  by  polarised  light,  are  extraordin- 
arily beautiful,  and  sometimes  simulate  the  appearance  of 
gorgeous  vegetation  or  of  feather  markings.  It  must  be 
admitted  that  to  draw  a  clear  line  between  such  purely 
automatic  molecular  arrangements  and  those  which  are 
brought  about  through  the  agency  of  life  is  by  no  means 
easy.  The  material  world  itself  when  closely  examined  is 
found  to  be  saturated  with  beauty  as  well  as  with  law  and 
order,  and  it  is  far  from  surprising  that  the  purely  inorganic 
realm  has  to  many  investigators  seemed  sufficient  to  ac- 
count for  everything.  Until  we  know  more  clearly  in 
what  way  life  acts  as  it  does,  until  we  understand  more 
fully  the  method  of  the  interaction  of  mind  and  matter, 
these  things  must  remain  a  matter  of  empirical  experience 
— admitted  but  not  explained.  The  formulation  of  a 
satisfactory  theory  must  await  the  attainment  of  deeper 
knowledge.  Meanwhile  all  the  careful  investigation  that 
is  going  on,  in  biology,  in  psychology,  and  in  every  direc- 
tion, is  all  to  the  good — by  whatever  provisional  hypothesis 
the  worker  is  guided. 

Page  93 

The  quotation  here,  and  that  on  page  97  also,  are  from 
the  writings  of  Rabindranath  Tagore  in  his  book  called 
Gitanjali,  which  he  wrote  both  in  Hindustani  and  in 
English,  and  which  constitutes  an  implicit  message  of  peace 


Explanatory  Notes  127 

and  harmony  and  mutual  understanding  from  the  East  to 
the  West. 

Page  95 

Professor  Miinsterberg  for  instance  has  indicated  his 
feeling  that  although  he  is  open  to  conviction  about  the 
reality  of  telepathy  if  he  be  forced  to  it  by  absolute  demon- 
stration, yet  the  fact  would  be  so  novel,  the  revolution  so 
great,  and  the  disarrangement  of  organised  knowledge  so 
profound,  that  almost  any  other  hypothesis  seems  to 
him  preferable  and  more  likely.  I  admit  that  telepathy 
when  universally  accepted  will  constitute  an  important 
enlargement  of  human  knowledge,  as  well  as  an  addition  to 
recognised  human  powers,  but  I  cannot  see  that  it  is  psy- 
chologically and  scientifically  so  revolutionary  as  it  evi- 
dently appears  to  the  eminent  philosopher  of  Harvard. 
I  trust  that  as  opportunity  offers  he  will  pursue  his  studies 
in  this  domain  and  will  ultimately  be  convinced  by  facts. 

Page  96 

It  appears  to  me  very  probable  that  telepathy  or  thought 
transference  is  a  form  of  direct  communication  between 
mind  and  mind,  apart  from  the  usual  physical  or  material 
concomitants.  If  so,  it  is  a  vitally  important  discovery, 
and  should  be  confirmed  by  each  one  for  himself  through 
careful  experiment  and  observation,  whenever  opportunity 
occurs;  so  that  gradually  it  may  be  recognised  as  an 
assured  fact,  not  only  by  the  few  who  have  as  yet  taken  the 
trouble  to  study  it,  but  by  all. 

Communication  with  discarnate  minds  is  a  further  step 
and  needs  separate  and  most  critical  proof,  but  if  any  such 
communication  ever  occurs  it  would  seem  to  be  rendered 
possible  by  the  exercise  of  telepathic  power.  Such  com- 
munication does  not  anyhow  appear  easy,  but  it  is  prob- 
ably by  some  method  akin  to  telepathy  that  it  can 


128          Presidential  Address 

sometimes  be  brought  about.  Mental  and  spiritual  opera- 
tions, such  as  prayer,  realised  as  efficacious  by  religious 
people,  appear  to  be  partially  of  this  nature. 

Page  97 

The  semi-jocular  parable  about  "Poynting's  Theorem" 
here  interjected  will  only  be  appreciated  by  physicists.  It 
is  a  mathematical  theorem  that  when  electric  and  magnetic 
fields  are  superposed  at  right  angles  to  each  other  a  third 
element  is  at  once  introduced, — an  element  of  progression 
or  advance  of  energy  at  right  angles  to  both,  and  of  value 
equal  to  their  vector  product.  It  is  in  this  way  that  light 
advances,  and  that  telegraphic  messages, wireless  and  other, 
are  conveyed.  Of  the  three  elements,  electricity,  mag- 
netism, and  motion,  when  any  two  are  supplied  the  third 
necessarily  supervenes.  This  is  the  basis  of  ordinary  dy- 
namos and  of  electric  motors,  as  well  as  of  many  other  more 
recondite  things.  The  Theorem  with  many  illustrations 
was  published  in  the  Philosophical  Transactions  of  the 
Royal  Society  for  1884. 

Page  98 

The  human  evil  in  the  world  can  be  regarded  as  the  price 
to  be  paid  for  human  freedom.  The  highest  product  of 
evolution  is  not  a  set  of  automata  mechanically  con- 
strained or  coerced  to  go  right,  but  human  beings,  knowing 
good  and  evil,  who  can  go  wrong  if  they  choose,  and  whose 
will  to  do  right  gradually  develops;  at  a  cost  in  suffering 
and  error,  great  indeed,  but  not  too  great  for  the  worth- 
whileness  of  the  ultimate  product.  This  point  of  view  is 
more  fully  explained  in  my  book  Man  and  the  Universe 
and  other  such  writings. 

The  outstanding  difficulty  always  felt  about  reconciling 
freedom  with  fixed  law  is  dealt  with  in  the  first  article  of 


Explanatory  Notes  129 

my  book  called  Modern  Problems  (Methuen),  where  what 
I  have  to  say,  whether  it  be  considered  useful  or  not,  re- 
presents or  summarises  the  results  of  very  careful  con- 
sideration. 

Page  103 

It  will  be  said,  it  has  indeed  been  frequently  said,  that 
the  evidence  ought  here  to  have  been  adduced.  To  this 
there  are  two  fairly  obvious  replies.  The  first  is  that  the 
evidence  for  any  kind  of  scientific  statements  is  quite 
inappropriate  to  an  address;  a  summary  and  an  allusion  is 
all  that  can  be  allowed,  and  nothing  more  is  attempted  in 
any  part  of  an  address  of  this  kind;  study  of  the  evidence 
is  necessarily  a  long  and  laborious  undertaking.  The 
second  is  that  even  though  some  parts  of  the  evidence  were 
offered,  not  in  an  address  but  in  a  paper  to  one  of  the  Sec- 
tions, it  would  as  yet  not  be  admitted.  The  attempt  has 
been  made.  Sir  William  Barrett  in  the  year  1876  read  a 
paper  on  the  evidence  for  telepathy  before  the  British 
Association  at  Glasgow,  but  its  publication  was  prevented. 

No,  the  time  is  not  ripe  for  discussing  the  evidence  for 
supernormal  psychical  experience  except  in  connection  with 
a  scientific  society  formed  for  the  purpose.  The  subject  is 
only  emerging  from  the  stage  expressed  by  the  first  para- 
graph on  page  77,  though  under  the  guidance  of  the  critical 
leaders  of  the  Society  for  Psychical  Research  it  is  emerging 
rather  fast.  The  members  of  that  Society  are  aware  that 
the  evidence  already  published — the  carefully  edited  and 
sifted  evidence  published  by  their  own  organisation — 
occupies  some  40  volumes  of  Journal  and  Proceedings ;  and 
some  of  them  know  that  a  great  deal  more  evidence  exists 
than  has  been  published,  and  that  some  of  the  best  evi- 
dence is  not  likely  to  be  published, — not  yet  at  any  rate. 
It  stands  to  reason  that  the  best  evidence  must  often  be  of 
a  very  private  and  family  character.  Many,  however,  are 
the  persons  who  are  acquainted  with  facts  in  their  own 


130         Presidential  Address 

experience  which  appeal  to  them  more  strongly  than  any- 
thing that  has  ever  been  published.  No  records  can  sur- 
pass first-hand  direct  experience  in  cogency. 

Nevertheless  members  of  the  Society  for  Psychical 
Research  are  also  aware,  or  ought  to  be,  that  no  one  crucial 
episode  can  ever  be  brought  forward  as  deciding  such  a 
matter.  That  is  not  the  way  in  which  things  of  import- 
ance are  proven.  Evidence  is  cumulative,  it  is  on  the 
strength  of  a  mass  of  experience  that  an  induction  is  ulti- 
mately made  and  a  conclusion  provisionally  arrived  at; 
though  sometimes  it  happens  that  a  single  exceptionally 
strong  instance,  or  series  of  instances,  may  clinch  it  for 
some  individual. 

But  indeed  the  evidence  in  one  form  and  another  has 
been  crudely  before  the  human  race  from  remote  antiquity, 
only  it  has  been  treated  in  ways  more  or  less  obfuscated  by 
superstition.  The  same  sort  of  occurrences  as  were  known 
to  Virgil  and  many  another  seer — the  same  sort  of  experi- 
ences as  are  found  by  folk-lore  students,  not  only  in  history 
but  in  every  part  of  the  earth  to-day — are  happening  now 
in  a  scientific  age  and  sometimes  under  scientific  scrutiny. 
Hence  it  is  that  from  the  scientific  point  of  view  progress 
is  at  length  being  made,  and  any  one  with  a  real  desire  to 
know  the  truth  need  not  lack  evidence  if  he  will  first  read 
the  records  with  an  open  mind  and  then  bide  his  time  and 
be  patient  till  an  opportunity  for  first-hand  critical  observ- 
ation is  vouchsafed  him.  The  opportunity  may  occur  at 
any  time:  the  readiness  is  all.  Really  clinching  evidence 
in  such  a  case  is  never  in  the  past;  a  prima  facie  case  for 
investigation  is  established  by  the  records,  but  real  con- 
viction must  be  attained  by  first-hand  experience  in  the 
present. 

Page  104 

The  quotation  is  from  the  writings  of  Symmachus,  an 
important  personage  in  the  4th  century  A.D.;  not  the  Pope 


Explanatory  Notes  131 

of  that  name,  but  a  pagan  proconsul  rather  hostile  to 
official  Christianity.  The  reference  is  Epp.,  x.,  54.  The 
passive  voice  of  the  verb  is  not  a  misprint;  it  appears 
intended  to  convey  the  sense  not  merely  of  arriving  at 
truth  but  of  being  assisted  or  guided  thereto. 


Publications  by 

Sir  Oliver  Lodge 


The  Ether  of  Space 

An  account  of  the  most  recent  researches  into  the  prop- 
erties of  the  fundamental  medium  of  which  the  material 
Universe  appears  to  be  composed.  1909. 

Modern  Views  of  Electricity 

A  well-known  exposition  of  fundamental  electrical  prin- 
ciples. New  edition  1907. 

Pioneers  of  Science 

A  course  of  popular  lectures  on  Astronomical  biography, 
being  sketches  of  the  lives  of  the  famous  early  astrono- 
mers and  their  work,  with  numerous  illustrations. 

Life  and  Matter 

A  discussion  of  the  scientific  foundations  of  religion; 
being  an  answer  to  Haeckel  and  a  speculation  concerning 
the  nature  of  life.  1905. 

Modern  Views  on  Matter 

Being  the  Romanes  Lecture  to  the  University  of  Oxford, 
delivered  in  1903,  on  the  new  discoveries  in  electricity  in 
connection  with  Radium  and  other  such  phenomena.  A 
pamphlet. 

Electrons 

Or  the  nature  and  properties  of  Negative  Electricity. 
A  treatise  on  the  most  recent  discoveries  in  the  pure 
science  of  Electricity.  1906. 

Easy  Mathematics;  Chiefly  Arithmetic 

A  comprehensive  summary  specially  addressed  to 
teachers,  parents,  self-taught  students,  and  adults.  In- 
tended to  make  the  subject  interesting.  1905. 


Signalling  through  Space  without  Wires 

First  published  in  1894  under  the  title  "  The  Work  of 
Hertz  and  his  Successors  "  ;  being  a  pioneer  treatise  on 
what  has  become  Wireless  Telegraphy.  1906. 

Lightning   Conductors    and    Lightning 
Guards 

A  technical  treatise  on  electric  waves  and  discharges 
generally,  for  Architects,  Electrical  Engineers,  and 
Physicists.  1892. 

Elementary  Mechanics 

A  text-book  for  Schools  and  Matriculation  Candidates. 

School  Teaching  and  School  Reform 

A  course  of  lectures  delivered  in  Birmingham  to  Teach- 
ers of  the  Midland  District.  1905. 

Parent  and  Child 

A  short  Treatise  on  the  Moral  and  Religious  Education 
of  Children. 

The    Substance    of  Faith    allied    with 
Science 

A  Catechism  for  Parents  and  Teachers.     1907. 

Man  and  the  Universe 

A  Study  of  the  Influence  of  the  Advance  in  Scientific 
Knowledge  upon  our  understanding  of  Christianity. 

The  Survival  of  Man 

A  Study  in  unrecognized  Human  Faculty. 

Reason  and  Belief 

Dealing  with  Incarnation,  and  with  the  truth  underlying 
ancient  doctrines. 

Modern  Problems 

Essays  on  a  large  number  of  controversial  topics.    1912,. 


The  Argument  against  Materialism 


Life  and  Matter 

A  Criticism  of  Professor  Haeckel's 
"A  Riddle  of  the  Universe" 

By  Sir  Oliver  Lodge 

Crown  8vo.  $1.00  net.  By  mail  $x.io 

The  author  fully  acknowledges  Haeckel's  service  to  scien- 
tific thought  in  introducing  Darwinism  into  Germany,  and 
he  admits  that  to  advanced  students  Haeckel's  writings  can 
do  nothing  but  good.  He  believes,  however,  that  to  some 
general  readers  they  may  do  harm,  unless  accompanied  by  a 
suitable  qualification  or  antidote,  especially  an  antidote 
against  the  bigotry  of  their  somewhat  hasty  and  destructive 
portions. 

"  Deserves  to  rank  with  the  best  contributions  by  Huxley 
to  scientific  literature;  while  from  the  scientific  standpoint 
it  is  timely  in  its  appearance,  brilliant  in  its  conception,  and 
admirable  in  execution.  It  should  be  welcomed  by  all  who 
are  interested  in  the  development  of  true  science,  but  who 
have  no  patience  for  blatant  materialism.  .  .  The  ut- 
terance of  a  scientist  eminent  for  his  wonderful  researches. 

.    .    .    The  book  is  full  of  interest  and  information." 

Rev.  James  M.  Owen,  Lynchburg,  Va. 

"  A  fascinating  reply  to  Haeckel's  materialistic  philosophy 
of  life.  The  arguments  are  sane  and  sound.  Lodge  is  a 
profound  scientist,  but  he  does  not  allow  his  scientific  know- 
ledge to  obscure  his  general  judgment." 

Providence  Journal, 


New  York— Q.  P.  Putnam's  Sons— London 


"  One  of  the  classics  of  the  nineteenth  century." 


The  Evolution  of  Man 

A  Popular  Scientific  Study 
By  Ernst  Haeckel 

Professor  at  Jena  University 

Translated  from  the  Fifth  (enlarged)  Edition  by 
Joseph  McCabe 

Two  volumes,  8vo,  with  30  Colored  Plates  and  512  other  Illustra- 
tions, together  with  60  Genealogical  Tables    .    .   Net,  $10.00 
New  Cheaper  Edition.    2  vols.    Illustrated.    Net,  $5.00 

The  work  is  a  comprehensive  statement  of  the  scientific 
grounds  for  evolution  as  applied  to  man.  It  does  not  deal 
with  religious  controversies,  and  is  scientific  throughout. 
The  work  is  unique  in  design,  which  is  carried  out  in  the 
last  edition  with  the  highest  degree  of  Haeckel's  literary 
and  artistic  skill.  Haeckel  has  always  been  distinguished 
for  pressing  the  combination  of  the  evidence  from  embry- 
ology with  the  evidence  of  zoology  and  paleontology.  In 
the  present  work  he  devotes  one  volume  broadly  to  embry- 
ology, or  the  evolution  of  the  individual,  and  the  second  to 
the  evolution  of  the  human  species,  as  shown  in  the  com- 
parative anatomy,  zoology,  and  paleontology.  The  last  few 
chapters  deal  in  detail  with  the  evolution  of  particular 
organs  right  through  the  animal  kingdom:  the  eye,  ear, 
heart,  brain,  etc.  Every  point  is  richly  illustrated  from 
Haeckel's  extensive  knowledge  of  every  branch  of  biology 
and  his  well-known  insistence  on  comparative  study. 

The  work  is  written  for  the  general  reader,  all  technical 
terms  being  explained,  and  no  previous  knowledge  being 
assumed  ;  but  the  scientific  reader,  too,  will  find  it  a  unique 
presentation  of  all  the  evidence  for  man's  evolution,  and 
especially  as  a  study  of  embryonic  development  in  the  light 
of  race-development. 

In  this  edition,  to  which  Haeckel  gave  six  months*  hard 
work,  the  plan  is  carried  out  with  great  skill,  and  the  illus- 
trations are  very  fine.  All  the  most  recent  discoveries  in 
every  branch  of  science  involved  are  included.  It  is  a 
thoroughly  up-to-date,  non-controversial,  most  comprehen- 
sive, and  scientific  treatise  On  the  evolution^ man  by  the 
greatest  living  authority  on  the  subject. 


New  York— Q.  P.  Putnam's  Sons— London 


The  most  valuable  production  since  Darwin's  "  Origin 
of  Species." 


The  Nature  of  Man 

Studies  in  Optimistic  Philosophy 
By  Elie  Metchnikoff 

Sub-Director  of  the  Pasteur  Institute,  Paris 

Translated  with  an  Introduction  by 

P.  Chambers  Mitchell 

Secretary  of  the  Zoological  Society 
Octavo.    Illustrated.    Popular  Edition.    $1.50  net.   By  mail,  $x.Cg 

It  Is  not  often  that  a  scientific  book  may  be  read  with 
ease,  profit,  and  pleasure  by  the  general  reader,  so  that 
M.  Metchnikoft's  book  comes  in  the  nature  of  an  agreeable 
surprise.  It  is  marked  by  a  refreshing  nawet&  and  a  large 
simplicity  which  are  characteristically  Russian.  The  scien- 
tific importance  of  this  work  is  so  great  that  it  is  spoken  of 
in  England  as  the  most  valuable  production  since  Darwin's 
Origin  of  Species. 

Opinions  of  the  Press 

*'An  extremely  interesting  and  typical  book.  ...  With  a  distin- 
guished frankness,  M.  Metchnikoff  defines  his  attitude  to  our  universal 
prepossessions.  It  is  his  theory  that  the  infirmities  of  age  are  to  be 
overcome.  If  there  be  ground  for  this  conception,  humanity  is  to  be 
profoundly  changed  and  what  we  call  life  now,  will  be  the  childhood 
and  youth  of  that  longer  and  larger  life."— H.  G.  WELLS,  in  London 
Speaker. 

"  Undoubtedly  a  great  book  (in  some  quarters  it  has  been  hailed  as 
the  greatest  since  Darwin's  famous  message  to  the  world)  and  should 
be  read  by  all  intelligent  men  and  women."—  The  Nation. 

"  A  book  to  be  set  side  by  side  with  Huxley's  Essays,  whose  spirit  It 
carries  a  step  further  on  the  long  road  towards  its  goal."— Mail  and 
Express. 

New  York— Q.  P,  Putnam's  Sons— London 


"  Remarkable  for  its  simple  language  and  clear 
style,  ^  ,  ,  Bears  the  stamp  of  a  production  of 
an  erudite  scientist  and  a  deep  t hin ker,"—  Science. 


THe  Prolongation  of 
Life 

Optimistic     Essays 

By  Elie  MetcHniKoff 
Author  of  "The  Mature  of  Man/'  etc. 

8vo.     Illustrated  Popular  Edition.    $1.7 5  net 
By  mail,  $1.90 

M.  filie  Metchnikoff  is  one  of  those  rare  scientists  who 
have  found  a  way  to  lay  hold  of  and  present  to  the  world  in 
untechnical  phraseology,  intelligible  to  the  lay  mind,  such 
results  of  his  researches  as  are  of  universal  interest  and  go 
straight  home  to  the  bosoms  and  business  of  intelligent  men. 
The  Nature  of  Man,  by  the  same  author,  was  one  of  the  most 
fascinating  books,  at  once  popular,  and  scientific,  which  have 
appeared  for  decades.  The  book  here  in  question  will  stand 
beside  it  as  a  worthy  companion  volume.  It  is  satisfactory 
to  report  that,  absorbed  as  Metchnikoff  is  in  '*  material " 
problems,  and  deep  as  he  is  in  the  mysteries  of  the  physical 
universe,  these  essays  show  him  to  be  an  optimist  who  speaks 
with  no  uncertain  voice. 

A  great  deal  of  attention  is  given  in  The  Prolongation  of 
Human  Life  to  the  subject  of  old  age  and  its  causes,  with 
scientific  observations  of  special  cases  among  human  beings 
and  the  lower  animals.  The  author  suggests  means  of  pro- 
longing life  and  health,  while  contemplating  natural  death 
with  serenity,  and  finding  that  agreeable  sensations  accompany 
its  approach.  Beyond  a  certain  point  it  seems  to  him  a  dis- 
advantage to  prolong  life.  Passing  on  from  these  mortuary 
lucubrations,  the  essays  concern  themselves  with  psychological 
matters,  with  optimism  and  pessimism  and  in  general  with 
questions  of  science  and  morals.  The  temperaments  of  certain 
great  men  are  analyzed  in  studies  that  have  for  their  subjects 
respectively  Byron,  Leopardi,  Schopenhauer,  and  Goethe.  In 
the  preface  the  author  says  that  he  has  avoided,  as  far  as 
possible,  repeating  points  which  have  been  sufficiently  treated 
in  The  Nature  of  Man. 


G.    P.    PUTNAM'S    SONS 

NEW  YORK  LONDON 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


DEC     9    1947 


2lJan'boH 
AN8    1953  L 


4UN    8  1953 


25:.lay'57AS 
REC 

MA  i  23 


LD  21-100m-9,'47(A5702sl6)476 


i^CL-    oj 

l5^0  M 


287946 

) 

Lt 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


